Method of controlling a secondary cooling device for a machine for the continuous casting of several metal products and secondary cooling device of a continuous casting machine

Abstract

Method of controlling a secondary cooling plant for a machine for the continuous casting of a plurality of metal products (P). The secondary cooling plant (12) comprises a plurality of cooling units (17) equipped with a plurality of nozzles (18), each of which has a plurality of delivery holes (19) from which, in each case, a flow of a refrigerant fluid (L) is delivered to a metal product (P) according to the cooling requirements on time.

Description

Technical Field

[0001] The present invention relates to a method for controlling primary and secondary cooling equipment in a machine for continuous casting of several metal products.

[0002] Specifically, the secondary cooling equipment acts on the metal product at the mold exit and along a roller conveyor located downstream of the mold. By way of example only, the cast metal product can be a billet, slab, or other known type. Background Technology

[0003] As is well known, in continuous casting, the metal product changes from a liquid state to a partially solid state, reaching complete solidification at a predetermined location downstream of the casting itself. During these steps, the surface of the metal product gradually thickens until it is completely solidified, containing a liquid metal core within the metal product.

[0004] Controlled heat removal from cast metal products is initially achieved through heat exchange via a primary cooling system. The primary cooling system comprises multiple cooling channels associated with or integrated into the containment walls of the mold (crystallizer).

[0005] A secondary cooling device is then provided downstream of the crystallizer. The secondary cooling device includes multiple nozzles, several rollers distributed in the middle for supporting and guiding the metal product, and a circuit for supplying one or more cooling fluids to the nozzles as described above.

[0006] The heat exchange mechanisms involved in secondary cooling equipment are radiation and convection.

[0007] Radiation is a heat exchange mechanism that occurs between two surfaces at different temperatures, such as the surface of a metal product and the surfaces of the rollers used to support and guide the latter.

[0008] In these types of applications, forced convection is determined by the delivery of one or more cooling fluids (and possibly mixtures thereof) onto the metal product to be cooled.

[0009] Nozzles are typically positioned between the support and guide rollers to direct one or more cooling fluids directly onto the metal product. For this purpose, cooling devices can be spaced apart to cover (and potentially overlap) the entire lateral dimension of the cast metal product. Furthermore, depending on the type of metal product to be cooled, the nozzles can deliver cooling fluid jets of different shapes.

[0010] Typically, in continuous casting machines, nozzles can be of the type that use only water or the type that uses both water and air.

[0011] For nozzles that only deliver water, water is delivered through a single orifice, or in conjunction with other orifices, and sprayed onto the casting product. To regulate the cooling, the water flow rate at the nozzle is varied to achieve a specific convective heat exchange effect. For nozzles that only deliver water, there is a minimum supply pressure below which the flow rate becomes unstable. The maximum supply pressure is typically the highest pressure available in the hydraulic supply circuit. The ratio between the maximum and minimum water flow rates defines a parameter called the Turn Down Ratio within the sector, hereinafter referred to as the TD ratio. A drawback of this type of nozzle and the method of controlling them is that it is impossible to increase the TD ratio because the minimum and maximum water flow rates are single and fixed and cannot be changed.

[0012] In the case of nozzles that deliver both water and air, adding air expands the nozzle's adjustment range, allowing for wider adjustment of the water flow rate, i.e., increasing the TD ratio. However, it should be noted that as air pressure increases, the water flow rate of the nozzle decreases.

[0013] Examples of nozzles that deliver water only and corresponding control methods are described in patent documents WO 2017 / 042059 A1, WO 2018 / 224304 A1 and US2019 / 0054520 A1.

[0014] Patent documents WO 2017 / 042059 A1 and WO 2018 / 224304 A1 describe a method for controlling several nozzles used for secondary cooling of a cast product, and a nozzle equipped with a selectively activatable / deactivatable valve that allows the nozzle to deliver intermittent flow, i.e., pulsed flow. Due to the use of the valve, a work cycle can be performed, operating at constant pressure, reducing the nozzle flow rate without the need for additional compressed air. However, using this type of nozzle and management method, it is impossible to achieve uniform cooling of the cast product. Furthermore, the intermittent delivery must be carefully calibrated according to the characteristics of the metal product leaving the mold and the specific nozzle operation position.

[0015] Patent document US2019 / 0054520A1 (US'520) describes a cooling device equipped with multiple nozzles supplied by a valve. Furthermore, US'520 A1 describes a method for managing the cooling device to supply the nozzles based on different flow rate requests. However, this management method does not allow for optimization, i.e., minimizing the total energy consumption of the secondary cooling equipment. In fact, as the flow rate increases, the supply pressure to the nozzles also increases, and the pressure drop is directly related to the power required by the water pump.

[0016] Therefore, there is a need to improve a method for controlling a secondary cooling device in a machine for the continuous casting of several metal products, which can overcome at least one of the disadvantages of the prior art.

[0017] In particular, an object of the present invention is to improve a method for controlling a secondary cooling device in a machine for the continuous casting of several metal products, the method allowing for an increased nozzle adjustment range, allowing for adjustment of water flow rate over a wider range, in other words, increasing the TD ratio.

[0018] Another object of the present invention is to improve a method for controlling a secondary cooling device in a machine for the continuous casting of several metal products, the method allowing control of the energy consumption for each required water flow rate value.

[0019] The applicant has designed, tested and implemented the present invention to overcome the disadvantages of the prior art and to obtain these and other objectives and advantages. Summary of the Invention

[0020] The invention is set forth and characterized in the independent claims. The dependent claims describe other features of the invention or variations of the main inventive concept.

[0021] To achieve the above objectives, a method is provided for controlling secondary cooling equipment in a machine for the continuous casting of several metal products according to the timely cooling requirements of the metal products.

[0022] The secondary cooling equipment includes a roller conveyor that supports the cast metal product and moves it along a moving axis, as well as multiple cooling units equipped with several nozzles.

[0023] Each nozzle is provided with at least two delivery holes through which refrigerant fluid is delivered to the metal product.

[0024] To cool metal products, the method provides the ability to activate the plurality of delivery orifices individually, sequentially, or in combination with each other, thereby delivering the correct flow rate of refrigerant fluid from one or more delivery orifices when the on-time cooling requirements of the metal products change, thereby controlling the energy consumption of a secondary cooling device that maintains its functionality over time to accommodate the on-time cooling requirements of the metal products.

[0025] The method is easy to manage and also allows for a high degree of flexibility in controlling the nozzles according to the on-time requirements of cast metal products in transit.

[0026] In each case, each nozzle is adjusted by activating one or more delivery orifices at the appropriate time, depending on the needs of the area where the metal product to be cooled.

[0027] The solution provides great flexibility in the secondary cooling control of cast metal products, where cooling is directly related to the on-time requirements of product transportation. This can be achieved by controlling the feed of each delivery orifice of the nozzle in a timely and precise manner.

[0028] Therefore, each nozzle can be autonomously connected to its own refrigerant fluid source, depending on how it is supplied and how it is operated, and each nozzle has a separate delivery orifice that can be activated as needed for on-time delivery.

[0029] According to one variation, nozzles operating on the same cross-section of a metal product are supplied by a single source.

[0030] According to another variant, multiple refrigerant fluid sources can also be provided.

[0031] Each cooling unit can be controlled independently of the others, or they can be controlled in the same way.

[0032] According to the present invention, two different refrigerant fluids, such as air or water, can also be supplied to one or more specific nozzles, or a single refrigerant mixture can be obtained by mixing the fluids.

[0033] According to one variation, a pulsed supply can also be used to supply one or more specific nozzles. In the case of controlling two or more nozzles with a pulsed supply, one or more specific nozzles may or may not be supplied with a constant pressure. Attached Figure Description

[0034] These and other aspects, features, and advantages of the invention will become apparent from the following description of some embodiments, with reference to the accompanying drawings, which are provided as non-limiting examples, wherein:

[0035] Figure 1 A schematic diagram of a continuous casting machine for metal products is shown.

[0036] Figure 2 The fluid dynamic connection to the nozzles of the cooling unit according to several embodiments described herein is schematically illustrated.

[0037] Figure 3 The diagram schematically illustrates a possible configuration for supplying cooling units arranged along a horizontal section of the casting line;

[0038] Figure 4 The possible configuration of the cooling unit along the vertical segment of the casting line is schematically shown;

[0039] Figure 5 A nozzle is schematically shown, with the delivery orifice in the nozzle being visible;

[0040] Figures 5a-5d It shows Figure 5 Possible variations of the conveying port;

[0041] Figure 6-8 The possible configurations of the cooling unit and nozzles relative to the metal product to be cooled and / or relative to the roller conveyor are shown.

[0042] Figure 9 This is a flow-pressure diagram illustrating the function and control mode of the nozzle according to the method of the present invention.

[0043] For ease of understanding, the same reference numerals are used to identify the same common elements in the figures where possible. It should be understood that elements and features of one embodiment can be readily incorporated into other embodiments without further clarification. Detailed Implementation

[0044] We will now refer in detail to various embodiments of the invention, with one or more examples of the invention illustrated in the accompanying drawings. Each example is provided by way of description of the invention and should not be construed as limiting it. For example, one or more features shown or described may be changed or adopted in other embodiments, or associated with other embodiments, to produce other embodiments, as long as they are part of one embodiment. It should be understood that the invention should include all such possible modifications and variations.

[0045] Before describing these embodiments, we must clarify that the application of this specification is not limited to the details of the construction and configuration of the components described below using the accompanying drawings. This specification may provide other embodiments and may be obtained or implemented in various other ways. We must also clarify that the wording and terminology used herein are for descriptive purposes only and should not be considered limiting.

[0046] Please refer to Figure 1 The described embodiments relate to a machine for continuously casting metal products, generally indicated by reference numeral 10. The machine 10 is configured to continuously cast several metal products P, for example, in the form of billets, steel billets, or slabs, or other forms known in the art.

[0047] During the casting process, the metal product P is first cooled by a primary cooling device 11, and then cooled by a secondary cooling device 12 managed by the control method according to the present invention.

[0048] Machine 10 includes a tundish 26 and a mold or crystallizer 14. The tundish 26 is capable of receiving liquid metal in a ladle 13, and the crystallizer 14 allows the liquid metal to pass through.

[0049] The primary cooling device 11 is directly associated with the crystallizer 14 in a known manner, while the secondary cooling device 12 is located downstream of the crystallizer 14.

[0050] The secondary cooling device 12 includes a roller conveyor 15 configured to guide and contain the metal product P leaving the crystallizer 14, and also remove heat from the metal product P, for example by radiation and conduction.

[0051] The roller conveyor 15 is capable of supporting the cast metal product P and moving it along a moving axis X, which may be curved, straight, or partially curved and partially straight.

[0052] The roller conveyor 15 may include a plurality of rollers 16, which may be appropriately spaced apart from each other, and whose axes of rotation are parallel to each other and orthogonal to the axis of movement X. The plurality of rollers 16 are configured to guide the metal product P along the casting line to the extraction area.

[0053] Therefore, the rotation axes of the plurality of rollers 16 located above the metal product P can be located on a plane parallel to and at a certain distance from the plane containing the rotation axes of the plurality of rollers 16 located below the metal product P. In this way, the plurality of rollers 16 define a channel and a stretching channel in which the cast metal product advances.

[0054] In several possible embodiments, the plurality of rollers 16 may also be arranged on the side of the product P so as to guide the product P along the side as well.

[0055] The secondary cooling device 12 may include a plurality of cooling components G, which are arranged sequentially along the continuous casting machine 10.

[0056] Each cooling assembly G may include multiple cooling units 17, each cooling unit 17 having one or more nozzles 18 arranged along the moving axis X. See details... Figure 2 The cooling assembly G includes three cooling units 18.

[0057] The cooling units 17 are adjacent to each other to cover a width at least equal to the maximum width of the metal product P that can be cast into the machine 10.

[0058] Each cooling unit 17 is capable of delivering a defined flow rate of at least one refrigerant fluid L to a specific area of ​​the metal product P.

[0059] Cooling unit 17 may be associated with roller conveyor 15, which cooperates with the latter to cool the metal product P during transport. Specifically, the plurality of nozzles 18 may be disposed between the plurality of rollers 16, either above the metal product P, below the metal product P, or possibly laterally. In this way, refrigerant fluid L can be guided unimpeded toward the entire metal product P.

[0060] According to some embodiments, the cooling unit 17 can be arranged either along a vertical segment or a curved segment, and may (though rarely) be arranged on a horizontal segment of the casting line, and can act on the bottom or top of the metal product P. Optionally, the cooling unit 17 can also act laterally relative to the metal product P.

[0061] Based on the desired cooling curve, cooling units 17 can determine the same cooling curve for the upper and lower surfaces of the metal product P, or they can determine different and independent cooling curves.

[0062] According to some embodiments, each nozzle 18 of each cooling unit 17 includes two or more delivery holes 19 for delivering refrigerant fluid L to the metal product P to be cooled.

[0063] According to some embodiments, each nozzle 18 (preferably 2 to 7 per cooling unit 17) includes two or more delivery holes 19, particularly at least two. Figures 5a-5d ), used to deliver refrigerant fluid L to the metal product P to be cooled.

[0064] Nozzles 18 can be appropriately distributed in the direction of the moving axis X. Figure 1 ), or it can be distributed transversely to the moving axis X ( Figure 2 In order to ensure cooling of any area of ​​the metal product P, the cooling unit 17 can be appropriately positioned relative to the metal product P (i.e., relative to the roller conveyor 15) and relative to the moving axis X, that is, at a desired angle, which can also reach about 45°, such as... Figure 7 As shown. In Figure 8 In an exemplary embodiment, the cooling unit 17 is arranged parallel to the rotation axis of the plurality of rollers 16, but the nozzles 18 are arranged in an interlaced configuration along the movement axis X, which describes an interlaced or "chessboard" configuration.

[0065] According to some embodiments, by opening or closing one or more connecting lines 24 associated with nozzle 18, the delivery orifice 19 of the same nozzle 18 can be supplied independently of each other. Figure 5 In addition, please refer to the following: Figure 2 The same delivery hole 19 of different nozzles 18 of the same or different cooling units 17 can be connected to the same connecting line 24.

[0066] In this and the following description, the term “homogeneous” refers to the delivery hole 19, which we mean that the delivery hole 19 of one nozzle 18 corresponds by geometric analogy to the delivery hole 19 of another nozzle 18 in the same cooling unit 17.

[0067] The delivery orifices 19 of the same nozzle 18 may have the same area of ​​the outlet portion, or different areas of the outlet portion 5d. The shape of the outlet portion of each delivery orifice 19 determines the shape of the jet of refrigerant fluid L, which may be, for example, blade-shaped or conical, or other shapes deemed suitable for cooling metal product P.

[0068] Please refer to Figure 2 The secondary cooling device 12 also includes a supply circuit 21 for supplying power to the cooling unit 17. The supply circuit 21 includes a plurality of valve assemblies 22, each of which may be associated with a respective cooling unit 17. Each valve assembly 22 may include at least one valve 22a for each of the corresponding delivery orifices 19 of the different nozzles 18 of the same cooling unit 17.

[0069] The supply circuit 21 is connected to at least one supply line 25, which is configured as a fluid connection device 23.

[0070] In this and the following description, by supply line 25 we mean the piping assembly connected to the pumping device at the initial end relative to the pumping device 23, and the piping assembly connected to the valve assembly at the end relative to the valve assembly 22.

[0071] Each valve 22a can be connected to the corresponding delivery port 19 of the nozzle 18 of the corresponding cooling unit 17 via the corresponding connecting line 24.

[0072] The cooling units 17 of the defined cooling assembly G can be started independently of each other, as each of them is controlled by a corresponding valve assembly 22.

[0073] In addition, each cooling component G can be supplied autonomously via its own supply line 25, which connects the pumping device 23 to the cooling component G as described above, or two or more cooling components G can be supplied via the same supply line 25.

[0074] According to some embodiments, such as Figure 3 As shown, a possible configuration of three cooling units 17 is illustrated, wherein each valve assembly 22 supplies power to at least two nozzles 18. In this configuration, in the first cooling unit 17, the valve assembly 22 defines two separate cooling zones, namely the top of the diagram, while in the second cooling unit 17, the valve assembly 22 defines a single, substantially uniform cooling zone at the bottom of the diagram.

[0075] according to Figure 4In some embodiments illustrated schematically, the cooling unit 17 may also be vertically arranged to cool the vertical segment of the metal product P at the outlet of the crystallizer 14, each connected via its own connecting line 24 to a corresponding delivery port 19 of the nozzle 18 in the cooling unit 17. Similarly, in this case, each valve assembly 22 may be provided with several valves 22a, each valve 22a connected via its own connecting line 24 to a homologous delivery port 19 of the nozzle 18 included in the cooling unit 17.

[0076] According to some embodiments, the flow rate of refrigerant fluid L and / or the pressure of the refrigerant fluid L flowing to valve assembly 22 can be appropriately controlled.

[0077] According to some embodiments, each valve assembly 22 may be provided with a supply line 25 (parallel supply), or the valve assembly 22 may be reached by a single supply line (series supply).

[0078] According to some embodiments, the cooling of the metal product P can be controlled by a surface temperature detector 27, such as... Figure 2 As shown.

[0079] According to several possible embodiments, the surface temperature detector 27 can allow for the verification of accurate temperature.

[0080] According to several possible embodiments, the surface temperature detector 27 can allow for feedback control of the flow rate of the refrigerant fluid L. In this case, the surface temperature detector 27 can detect the temperature of a specific area of ​​the metal product P and send a corresponding operating signal to the control and command unit 20.

[0081] According to some embodiments, the flow rate of the refrigerant fluid L supplied by the cooling unit 17 is controlled by a control and command unit 20, which is based on a surface temperature estimated using a point-to-point mathematical model. The flow rate of the refrigerant fluid L is modified such that the temperature estimated by the mathematical model corresponds to the desired temperature.

[0082] According to some embodiments, the control and command unit 20 may be configured to receive a series of process operation parameters.

[0083] The process operating parameters can be selected from a set of parameters, including the volumetric flow rate of the metal product P, the temperature measured zone by zone on the metal product P, the chemical composition of the metal product P (or steel grade), the form of the product, or other process parameters that are considered unique.

[0084] The control and command unit 20 is also configured to process operating command signals and send them to the device 23 to pump refrigerant fluid L. The operating command signals determine the flow rate Q of refrigerant fluid L required to cool the metal product P.

[0085] According to the embodiments described herein, the refrigerant fluid L can be water, which may be treated. However, the use of a refrigerant mixture comprising at least a first liquid refrigerant fluid (e.g., water) and at least a second air-like refrigerant fluid (e.g., air) is not excluded. It is evident that the use of a refrigerant fluid or mixture can determine variations in the system regulating the pumping of these fluids.

[0086] According to some embodiments, a method for controlling the above-mentioned secondary cooling device 12 is provided.

[0087] According to one aspect of the invention, the method provides for activating the plurality of delivery orifices 19 individually, sequentially, or in combination thereof, such that the flow rate Q of the refrigerant fluid L required to cool the metal product P varies each time the on-time cooling demand of the metal product P changes.

[0088] The flow rate Q is determined based on the cooling required on the metal product P, and energy consumption is minimized by opening the correct and necessary number of delivery orifices 19, which allows for the minimum pressure drop of the supply circuit 21.

[0089] Depending on the specific region of the metal product P to be cooled, the required flow rate Q of the refrigerant fluid L can vary along the moving axis X or in the lateral direction relative to the moving axis X. The required flow rate Q of the refrigerant fluid L can depend on, for example, the chemical composition of the metallic material in which the metal product P is composed, the temperature distribution that may be detected in a specific region (e.g., a cross-section) of the metal product P, the flow rate of the metal product P, and / or other operating parameters.

[0090] When the flow rate Q of the refrigerant fluid L required to cool the metal product P or a specific area thereof increases or decreases, the delivery orifices 19 of the nozzle 18 are determined to open or close sequentially from the first to the last or from the last to the first, so as to minimize the supply pressure of the refrigerant fluid L to the supply circuit 21, thereby minimizing the pressure drop and reducing the power required for the pumping device 23 to operate at the same flow rate Q.

[0091] According to a possible embodiment, the method can detect the temperature distribution of a defined area of ​​the metal product P, send the detected temperature value to a control and command unit 20, which also receives at least one value of the flow rate of the metal product P. The control and command unit 20 processes the temperature and flow rate values ​​and transmits an operation signal to a device 23 that pumps the refrigerant fluid L. The operation signal is a signal that allows the delivery of the refrigerant fluid L flow rate Q required to cool the metal product P, selectively opening the delivery orifice 19 to minimize the pressure drop in the supply circuit 21 and thus minimize the power required to operate the pumping device 23.

[0092] according to Figure 9The example shown illustrates the pressure-flow rate profile of a nozzle 18 with three delivery orifices 19, specifically the first delivery orifice 19a, the second delivery orifice 19b, and the third delivery orifice 19c in this particular case.

[0093] When the flow rate Q of the refrigerant fluid L required to cool the metal product P or a specific area of ​​it requires the first supply pressure p1 of the first delivery orifice 19a of the nozzle 18 to be lower than the first minimum pressure p01 of the first delivery orifice 19, the entire nozzle 18 is deactivated, that is, it does not deliver the flow rate Q of the refrigerant fluid.

[0094] When the flow rate Q of the refrigerant fluid L required to cool the metal product P requires a first supply pressure p1 of the first delivery port 19a to be greater than a first minimum pressure p01 of the first delivery port 19a, and a second supply pressure p1+2 associated with the second delivery port 19b and the first delivery port 19a is lower than a second minimum pressure p02 associated with the second delivery port 19b and the first delivery port 19a, the first delivery port 19a is activated to deliver the refrigerant fluid L at a flow rate Q.

[0095] When the flow rate Q of the refrigerant fluid L required to cool the metal product P needs to be greater than the second supply pressure p1+2 of the second minimum pressure p02, and the third supply pressure p1+2+3 of the third supply pressure p1+2 relative to the third supply port 19c associated with the second supply port 19b and the first supply port 19a, the total flow rate Q of the refrigerant fluid L supplied by the first supply port 19a and the second supply port 19b relative to the third supply port 19c and the second supply port 19b and the first supply port 19a.

[0096] When the flow rate Q of the refrigerant fluid L required to cool the metal product P needs to be greater than the third supply pressure p1+2+3 of the third minimum pressure p03, the total flow rate Q of the refrigerant fluid L delivered by the first delivery port 19a, the second delivery port 19b, and the third delivery port 19c is delivered.

[0097] In other embodiments of the control method, the delivery holes 19a, 19b and 19c may also be activated in different orders and combinations as described above.

[0098] The first minimum pressure p01, the second minimum pressure p02, and the third minimum pressure p03 can be the same, such as... Figure 9 As shown, they can also be different from each other. In particular, the minimum pressure is the critical pressure value, below which the flow of refrigerant fluid L in nozzle 18 becomes unstable.

[0099] The delivery orifice 19 of nozzle 18 is further characterized by a maximum supply pressure pmax, which is typically the maximum supply pressure available in the supply circuit of refrigerant fluid L.

[0100] Obviously, the control method can be easily extended to a number of nozzles 18 equal to or greater than two.

[0101] Obviously, without departing from the scope and domain of the present invention, modifications and / or additions can be made to the control method of the secondary cooling device 12 of the machine 10 for continuous casting of metal products as described above.

[0102] It is also clear that, although the invention has been described with reference to some specific examples, those skilled in the art will certainly be able to implement many other equivalent forms of the method for controlling a secondary cooling device in a machine for continuous casting of metal products, which have the features described in the claims and are therefore within the scope of protection defined therein.

[0103] In the following claims, the reference numerals in parentheses serve only for ease of reading and should not be considered as limiting factors of the field of protection claimed in any particular claim.

Claims

1. A method for controlling a secondary cooling device in a machine for continuous casting of several metal products, said secondary cooling device (12) comprising a roller conveyor (15) for moving metal products (P) along a moving axis (X), and a plurality of cooling units (17) equipped with a plurality of nozzles (18), each nozzle (18) having a plurality of conveying orifices (19), wherein a refrigerant fluid (L) is conveyed from the plurality of conveying orifices (19) to the metal product (P) in each case according to timely cooling requirements, characterized in that, The method provides, through a control and command unit (20), the activation of the plurality of delivery orifices (19) individually, sequentially, or in combination thereof, such that the flow rate (Q) of the refrigerant fluid (L) required to cool the metal product (P) varies each time the on-time cooling demand of the metal product (P) changes, wherein when the flow rate (Q) of the refrigerant fluid (L) increases or decreases, the plurality of delivery orifices (19) of the corresponding nozzles (18) are sequentially opened or closed from the first to the last, supplying the plurality of delivery orifices (19) with a minimum delivery pressure to obtain the flow rate (Q), wherein the secondary cooling device (12) includes a supply circuit (21) for supplying the plurality of cooling units (17), the supply circuit (21) including a plurality of valve assemblies (22), wherein each valve assembly (22) is associated with a respective cooling unit (17), and each valve assembly (22) includes at least one valve (22a) for the respective homologous delivery orifices (19) of different nozzles (18) of the same cooling unit (17). The first delivery hole (19a) delivers the flow rate (Q) of the refrigerant fluid (L) required to cool the metal product (P) when a first supply pressure (p1) of a first delivery hole (19a) of one or more of the nozzles (18) is greater than a first minimum pressure (p01) of the first delivery hole (19a) and when a second supply pressure (p1+2) relative to a second delivery hole (19b) cooperating with the first delivery hole (19a) is lower than a second minimum pressure (p02) relative to the second delivery hole (19b) together with the first delivery hole (19a), the first delivery hole (19a) delivers the flow rate (Q) of the refrigerant fluid (L).

2. The method as described in claim 1, characterized in that, When the flow rate (Q) of the refrigerant fluid (L) required to cool the metal product (P) or a specific area thereof requires the first supply pressure (p1) of the first delivery orifice (19a) of one or more of the nozzles (18) to be lower than the first minimum pressure (p01) of the first delivery orifice (19a), the nozzle (18) is deactivated, that is, the nozzle (18) does not deliver refrigerant fluid (L).

3. The method as described in any one of the preceding claims, characterized in that, When the flow rate (Q) of the refrigerant fluid (L) required to cool the metal product (P) needs to be greater than the second supply pressure (p1+2) relative to the second minimum pressure (p02) of the second delivery port (19b) that cooperates with the first delivery port (19a), the first delivery port (19a) and the second delivery port (19b) together deliver the flow rate (Q) of the refrigerant fluid (L) relative to the second delivery port (19b) and the first delivery port (19a).

4. The method as described in claim 3, characterized in that, The first minimum pressure (p01) and the second minimum pressure (p02) are the same.

5. The method as described in claim 3, characterized in that, The first minimum pressure (p01) and the second minimum pressure (p02) are different.

6. A secondary cooling device (12) for a continuous casting machine, the secondary cooling device (12) comprising a roller conveyor (15) for moving a metal product (P) along a moving axis (X), a plurality of cooling units (17) equipped with a plurality of nozzles (18), each nozzle (18) having a plurality of conveying orifices (19), wherein, according to timely cooling requirements, a refrigerant fluid (L) is conveyed from the plurality of conveying orifices (19) to the metal product (P) in each instance, characterized in that, It includes a control and command unit (20) configured to implement the method as described in any one of claims 1 to 5.

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