Cooling unit for a laminar cooling system

Abstract

The invention relates to a cooling unit of a laminar cooling device (1). At least one cooling unit of the cooling device is arranged above and below a strip to be cooled in order to supply the strip with a cooling liquid, comprising a central inlet (2), via which cooling liquid is supplied, a distributing tube (3) which is supplied with cooling liquid by the central inlet (2), and a number of supplying units (4) which are supplied with cooling liquid from the distributing tube (3). Each supplying unit (4) is equipped with a number of cooling nozzles (5), via which cooling liquid is discharged onto the strip. In order to minimize the influence of the number of supplying units which are switched on or switched off, and thus have as little expenditure as possible, a volumetric flow rate regulating valve is arranged in or in front of the central inlet (2), said regulating valve being used to conduct a defined volume of cooling liquid through the central inlet (2) per unit of time.

Description

[0001] Cooling unit of a laminar cooling device

[0002] The invention relates to a cooling group of a laminar cooling device, at least one of which is arranged above and below a belt to be cooled in order to supply the belt with a cooling liquid, comprising a central inlet through which cooling liquid is supplied, a distribution pipe supplied with cooling liquid from the central inlet and a number of supply units which are supplied with cooling liquid from the distribution pipe, wherein a number of cooling nozzles are arranged on each supply unit through which cooling liquid is applied to the belt.

[0003] A typical laminar cooling device (laminar cooling section) for cooling rolled metal strip is divided into individual cooling groups. Each cooling group consists of a central inlet and a distribution pipe leading to at least four or more cooling units (cooling beams) located above or below the metal strip to be cooled. The groups located immediately downstream of the rolling process are preferably supplied with a higher flow rate than those located at the end of the cooling process or those located just before the coiler.

[0004] Examples of cooling devices of this type are disclosed by CN 103861879, CN 102397888, CN 102513385, and CN 203419952 U. Setting a defined cooling curve requires a specific cooling strategy, according to which individual application units of a cooling group release the required quantities of water to achieve the specified cooling curve and maintain the desired target temperature during coiling (coiling temperature) even with changing process parameters (e.g., changes in rolling speed or final rolling temperature). This requires that the exact intended quantity of water, ideally the same, always exits from each application unit, regardless of the switching state of the cooling group.According to a previously known solution, the supply to a cooling unit is provided by an elevated tank filled with cooling water, which ensures a constant pre-pressure at the cooling unit's inlet. The switching valves are located immediately upstream of the individual application units and are either fully open or fully closed, depending on whether cooling water is to be applied to the metal belt from the respective unit or not.

[0005] A disadvantage of this configuration is that the normally constant pre-pressure leads to a pressure loss depending on the flow velocity in the piping systems, which reduces the flow rate of water in the aeration units depending on the switching state. This also means that the individual flow rate through an aeration unit depends on the switching state of the entire group. Therefore, a cooling strategy for belt cooling can only operate imprecisely.

[0006] A second known solution involves installing a flow control unit upstream of each spray unit. This allows the desired flow rate to be set independently of the inlet pressure. However, this solution has the disadvantage of requiring significant effort and therefore a substantial investment; furthermore, the control engineering effort is considerably higher than in the previously described variant. The invention therefore aims to design a laminar cooling device of the type mentioned above in such a way that the influence of the number of spray units switched on or off on the water flow velocity and quantity remains minimal. At the same time, it is essential to ensure that the investment costs remain as low as possible.The solution to this problem according to the invention is characterized in that a flow control valve is arranged in or upstream of the central inlet, with which a defined volume of coolant is directed through the central inlet per unit of time. The solution according to the invention ensures, in a simple yet effective manner, that the cooling units have access to precisely the amount of coolant required to adjust the cooling rate. Pressure loss over the short pipe section is negligible when considering the design features described below, so that the cooling units of a cooling group can be supplied uniformly.

[0007] The laminar cooling device is preferably designed to generate a volume flow of between 30 and 200 m³ / h by means of a device arranged above or below the strip to be cooled. 3 / m 2 to direct h per side of the tape.

[0008] The cross-section of the distribution pipe and the cross-section of the application units are preferably in a ratio of at least 1.0; a ratio of at least 1.5 is particularly preferred.

[0009] In the case of the laminar cooling device being arranged above the strip to be cooled, it is preferably designed such that the ratio of the flow velocity in the distribution pipe to the flow velocity in the application unit is in the range between 0.6 and 3.0. In the case of the laminar cooling device being arranged below the strip to be cooled, the ratio of the flow velocity in the distribution pipe to the flow velocity in the application unit is preferably in the range between 0.2 and 1.0.

[0010] The Reynolds number in the central inlet, in the distribution pipe and / or in the application units is preferably between 2,000 and 3,000. The Reynolds number is the product of the density of the cooling medium, the flow velocity, and the characteristic length (reference length) of the body through which the fluid flows, divided by the dynamic viscosity of the cooling medium.

[0011] The laminar cooling device is preferably designed such that the pressure in an actuation unit arranged above the belt is maintained above 0.05 bar.

[0012] It is preferably designed such that the pressure in an actuation unit arranged below the belt is kept above 0.025 bar.

[0013] The setting of the volume flow control valve is preferably determined from the relationship

[0014] determined, whereby the total target volume flow and

[0015] Qs { 4.n) the target partial volume flows in the individual

[0016] The application units (4.1, 4.2, ...) are used. In this case, it is preferably provided that the target volume flow is controlled by a control loop with which the volume flow control valve is changed in its setting, preferably taking into account a correction value for the flow rate setting.

[0017] The cooling water volume for each application unit is calculated according to a predefined cooling strategy. The total coolant requirement is then calculated, according to the formula above, as the sum of the cooling water volumes for the individual application units (1 to n).

[0018] The amount of cooling water in each application unit can be the same or different in each unit.

[0019] Preferably, at least six, and especially preferably at least eight, pressure units are arranged consecutively in a cooling group in the conveying direction of the belt.

[0020] The proposed concept therefore involves placing a flow control valve upstream of each cooling unit, which regulates the desired flow rate within the unit independently of the inlet pressure. Furthermore, the

[0021] The diameter ratios (cross-sectional ratios) of the supply lines to the chilled beams are specifically selected. This ensures that switching on or off any of the group's air handling units (regardless of their configuration) has no effect whatsoever on the local flow rate of an individual air handling unit.

[0022] A cooling section controlled in groups is therefore preferred, in which a specific application rate of between 30 and 200 m³ is used. 3 / m 2h is provided per side of the conveyor belt. The cross-sectional ratio between the distributor pipe and the cooling beam is at least 1.0, preferably at least 1.5. The velocity ratio between the distributor pipe and the impingement unit of the upper cooling group is preferably between 0.6 and 3.0; that of the lower cooling group is preferably between 0.2 and 1.0.

[0023] The operating pressure of the upper impingement unit is at least 0.050 bar, that of the lower impingement unit at least 0.025 bar.

[0024] The proposed solution provides a cooling system for cooling a slab or strip, with which an improved cooling effect can be achieved.

[0025] The coolant flow rate is measured and controlled directly, ensuring precise adherence to a predetermined flow rate. At least one control loop is provided to regulate a flow rate range. This includes at least one flow meter and at least one control valve, positioned at appropriate locations along the supply line.

[0026] This allows the amount of coolant and the area affected to be varied.

[0027] The cooling system and its cooling capacity are preferably integrated into a process model.

[0028] The proposed device and corresponding method enable improvements in the control accuracy and speed of the cooling process (for example, with regard to belt speedup, microstructure adjustment, and belt inhomogeneity). An embodiment of the invention is shown in the drawing. The single figure schematically depicts a cooling unit of a laminar cooling device that cools the top surface of a belt (not shown). In this embodiment, the cooling unit of a laminar cooling device 1 comprises five cooling units 4 in the form of cooling bars, arranged sequentially in the conveying direction F of the (not shown) belt. Preferably, 6 to 8 cooling units 4 are combined to form a cooling unit. For the sake of simplicity, this has been omitted in Figure 1.The cooling beams 4 are equipped with a multitude of cooling nozzles 5 that apply coolant from above onto the (not shown) belt.

[0029] The coolant is supplied via a central inlet 2, from which a distribution pipe 3 is fed with coolant. From the distribution pipe 3, the coolant reaches the cooling beams 4.

[0030] It is essential that a volume flow control valve 6 is arranged in or in front of the central inlet 2, with which a defined volume of coolant is directed through the central inlet 2 per time.

[0031] The flow rate through the central inlet is measured directly by means of the flow meter 7 and regulated based on the measurement result. For each flow rate range, at least one control loop 8 is provided, in which the measured actual value is compared with the setpoint value and, if necessary, the control valve 6 is adjusted using a correction value (corr.) to regulate the flow rate. Depending on the flow rate, at least one flow meter and / or one control valve is installed on separate lines. Valves 9 allow the flow rate of individual spray units 4.n to be adjusted, as well as their activation or deactivation. This allows not only the cooling rate but also the spray area to be varied. Alternatively, valve 9 can also be configured as a simple switching valve (on / off) solely for setting the control button.By integrating it into a control system, changes in the setpoint for coolant demand with regard to the cooling rate and / or the cooling area of ​​individual application units can be compensated for without negative effects.

[0032] The coolant quantity and the contact area can be varied. The control device regulates an orifice against the back pressure (at least 40% of the total pressure loss), thus enabling stepless, volume-controlled water supply, particularly between 40% and 100% of the total water quantity.

[0033] Flow measurement allows the desired switching state to be checked or monitored in automation.

[0034] Additionally, functionality can be provided for checking the functional unit of the cooling system or the pressure-discharge units. Flierzu can enable an active response during operation within the framework of a process model. Malfunctions can be detected during the maintenance cycle.

[0035] The entire water management system can be integrated into this process, and the pump control can be managed based on the calculated and set water volumes. This ensures that only the amount of water required for cooling is released by the pumps.

[0036] Reference symbol list

[0037] 1 Cooling unit of the laminar cooling device 2 Central inlet

[0038] 3 distribution pipe

[0039] 4 Pressurization unit (chilled beams)

[0040] 4.1 Pressurization unit (chilled beam)

[0041] 4.2 Cooling unit (chilled beam) 4.3 Cooling unit (chilled beam)

[0042] 4.4 Pressurization unit (chilled beam)

[0043] 4.n Pressurization unit (chilled beam)

[0044] 5 Cooling nozzle

[0045] 6 Flow control valve

[0046] 7 Flow measurement

[0047] 8 Control loop

[0048] 9 valve

[0049] F Conveyor direction

Claims

Patent claims:

1. Cooling group of a laminar cooling device (1), at least one of which is arranged above and below a belt to be cooled, in order to a belt to be supplied with a cooling liquid, comprising a central inlet (2) through which cooling liquid is supplied, a distribution pipe (3) supplied with cooling liquid from the central inlet (2) and a number of supply units (4) which are supplied with cooling liquid from the distribution pipe (3), wherein each supply unit (4) has a number of cooling nozzles (5) is arranged, via which the coolant is applied to the belt, characterized in that a volume flow control valve (6) is arranged in or in front of the central inlet (2), with which a defined volume of coolant is directed through the central inlet (2) per time.

2. Cooling group of a laminar cooling device according to claim 1, characterized in that it is designed to provide a volume flow of between 30 and 200 m³ by means of a device arranged above or below the belt to be cooled. 3 / m 2 to direct h per side of the tape.

3. Cooling group of a laminar cooling device according to claim 1 or 2, characterized in that the cross-section of the distribution pipe (3) and the cross-section of the application units (4) are in a ratio of at least 1.

0.

4. Cooling group of a laminar cooling device according to claim 3, characterized in that the cross-section of the distribution pipe (3) and the cross-section of the application units (4) are in a ratio of at least 1.

5.

5. Cooling group of a laminar cooling device according to one of claims 1 to 4, characterized in that, in the case of the arrangement of the laminar cooling device (1) above the strip to be cooled, it is designed such that the ratio of the flow velocity in the distributor pipe (3) to the flow velocity in the The operating unit (4) is in the range between 0.6 and 3.

0.

6. Cooling group of a laminar cooling device according to one of claims 1 to 5, characterized in that, in the case of the arrangement of the laminar cooling device (1) below the strip to be cooled, it is designed such that the ratio of the flow velocity in the distributor pipe (3) to the flow velocity in the The operating unit (4) is in the range between 0.2 and 1.

0.

7. Cooling group of a laminar cooling device according to one of claims 1 to 6, characterized in that the Reynolds number in the central inlet (2), in the distribution pipe (3) and / or in the application units (4) is between 2,000 and 3,000.

8. Cooling group of a laminar cooling device according to one of claims 1 to 7, characterized in that it is designed to control the pressure in a to maintain the pressure of the pressure-inducing unit (4) arranged above the belt above the belt above 0.05 bar.

9. Cooling group of a laminar cooling device according to one of claims 1 to 8, characterized in that it is designed to maintain the pressure in an actuation unit (4) arranged below the belt above 0.025 bar.

10. Cooling group of a laminar cooling device according to one of claims 1 to 9, characterized in that the setting of the volume flow control valve (6) is determined from the relationship is determined, whereby the total target volume flow and ( 4.n) the target partial volume flows in the individual The operating units (4.1 , 4.2, ...) are.

11. Cooling group of a laminar cooling device according to claim 10, characterized in that the target volume flow (Qs O i with a Control section (8) is controlled, with which the volume flow control valve (6) is changed in its setting, preferably taking into account a correction value (Corr.) for flow rate adjustment.

2. Cooling group of a laminar cooling device according to one of claims 1 to 11, characterized in that at least six, preferably at least eight, application units (4) are arranged successively in the conveying direction (F) of the belt.