Cooling unit of a laminar cooling device

Abstract

A cooling group for a laminar cooling device, including at least one cooling unit arranged above and below a strip to be cooled in order to supply the strip with a cooling liquid, including a central inlet via which cooling liquid is supplied, a distributing tube supplied with cooling liquid by the central inlet, and a number of supplying units supplied with cooling liquid from the distributing tube. Each supplying unit has a number of cooling nozzles 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. The regulating valve is used to conduct a defined volume of cooling liquid through the central inlet per unit of time.

Claims

1. A cooling group for a laminar cooling apparatus arrangeable above and below a strip to be cooled in order to apply a cooling liquid to the strip, comprising: a central inflow via which the cooling liquid is supplied; a distributor tube that is supplied with the cooling liquid from the central inflow; a number of application units that are supplied with the cooling liquid from the distributor tube; a number of cooling nozzles arranged on each of the application units for applying the cooling liquid to the strip; a volume flow-regulating valve arranged in or in front of the central inflow and configured so as to conduct a defined, variable volume of the cooling liquid through the central inflow per unit of time, wherein setting of the volume flow-regulating valve is determined from a relationship
{dot over (Q)}.sub.target=Σ.sub.i=1.sup.n{dot over (Q)}.sub.target.sup.(4.n), where {dot over (Q)}.sub.target is a total target volume flow rate, and {dot over (Q)}.sub.target.sup.(4.n) is a target partial volume flow rate in the individual application units; and a closed loop control system configured to continuously regulate the target volume flow ({dot over (Q)}.sub.target) by changing the setting of the volume flow regulating valve, wherein the closed loop control system includes a throughflow meter for measuring the through flow through the central inflow, and a comparator configured to compare a measured actual value with the target value of the volume flow rate.

2. The cooling group for a laminar cooling apparatus according to claim 1, wherein the cooling group is configured to conduct through the laminar cooling apparatus arranged above or below the strip to be cooled a volume flow rate of the cooling liquid of between 30 and 200 m.sup.3/m.sup.2 h per strip side.

3. The cooling group for a laminar cooling apparatus according to claim 1, wherein a ratio between a cross section of the distributor tube and a cross section of each of the application units is at least 1.0.

4. The cooling group for a laminar cooling apparatus according to claim 3, wherein the ratio between the cross section of the distributor tube and the cross section of each of the application units is at least 1.5.

5. The cooling group for a laminar cooling apparatus according to claim 1, wherein, when the laminar cooling apparatus is arranged above the strip to be cooled, said laminar cooling apparatus is designed so that a ratio of flow speed in the distributor tube to flow speed in the application units is in the range between 0.6 and 3.0.

6. The cooling group for a laminar cooling apparatus according to claim 1, wherein, when the laminar cooling apparatus is arranged below the strip to be cooled, said laminar cooling apparatus is designed so that a ratio of flow speed in the distributor tube to flow speed in the application units is in the range between 0.2 and 1.0.

7. The cooling group for a laminar cooling apparatus according to claim 1, wherein a Reynolds number in the central inflow, in the distributor tube and/or and in the application units lies between 2000 and 3000.

8. The cooling group for a laminar cooling apparatus according to claim 1, wherein the cooling group is configured to maintain pressure in an application unit arranged above the strip above 0.05 bar.

9. The cooling group for a laminar cooling apparatus according to claim 1, wherein the cooling group is configured to maintain pressure in an application unit arranged below the strip above 0.025 bar.

10. The cooling group for a laminar cooling apparatus according to claim 1, wherein the closed loop controlled system is configured to regulate the target volume flow rate({dot over (Q)}.sub.target) by taking into consideration a correction value for throughflow rate setting.

11. The cooling group for a laminar cooling apparatus according to claim 1, wherein at least six application units are arranged in succession in a conveying direction of the strip.

12. The cooling group for a laminar cooling apparatus according to claim 11, wherein at least eight application units are arranged in succession in a conveying direction of the strip.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The proposed apparatus or the corresponding procedure make it possible to achieve an improvement with regard to the regulation accuracy and the regulation speed of the cooling application (for example with regard to the “strip speed-up”, the microstructure settings and the inhomogeneity of the strip).

DETAILED DESCRIPTION OF THE INVENTION

(2) An exemplary embodiment of the invention is illustrated in the drawing. The sole FIGURE shows, in a schematic illustration, a cooling group of a laminar cooling apparatus, which cools the top side of a strip (not illustrated).

(3) In the exemplary embodiment, the cooling group of a laminar cooling apparatus 1 comprises five application units 4 in the form of cooling bars, which are arranged in succession in the conveying direction F of the strip (not illustrated). Preferably, 6 to 8 application units 4 are combined to form a cooling group. For reasons of simplified illustration, this has been dispensed with in FIG. 1. The cooling bars 4 are equipped with a multiplicity of cooling nozzles 5, which apply cooling medium from above onto the strip (not illustrated).

(4) The supply of cooling medium is realized through a central inflow 2 from which a distributor tube 3 is fed with cooling medium. The cooling medium passes from the distributor tube 3 to the cooling bars 4.

(5) What is significant is that a volume flow-regulating valve 6 is arranged in or in front of the central inflow 2, by way of which regulating valve a defined volume of cooling liquid is conducted through the central inflow 2 per unit of time.

(6) The throughflow through the central inflow is directly measured by means of the throughflow measurement means 7 and regulated on the basis of the measurement result. For each throughflow rate range, there is provided in each case (at least) one closed loop controlled system 8, in which the measured actual value is compared with the target value and, if appropriate, the regulating valve 6 is changed in terms of its setting by way of a correction value (corr.) for throughflow rate setting. At least one throughflow meter and/or one regulating valve are/is used at separate lines according to the throughflow rate.

(7) By way of valves 9, individual application units 4.n can be set in terms of their throughflow rate and also activated or deactivated. In this way, it is possible to vary not only the cooling rate but also the application surface area. Alternatively, the valve 9 may also be designed solely as a switching valve (on/off) for exclusive setting of the switching surface. Through incorporation into a closed loop control, it is possible to compensate for changes to the target value specification of the cooling medium requirement, with respect to the cooling rate and/or the cooling surface area, of individual application units without any adverse effects.

(8) The quantity of cooling medium and the application surface area can be varied here. The regulating device regulates, counter to the counterpressure (at least 40% of the total pressure loss), an aperture and thus makes possible stepless, volume-controlled supply of a quantity of water, in particular between 40% and 100% of the total quantity of water.

(9) The throughflow measurement allows the desired switching state to be checked, or monitored in the automation system.

(10) Additionally, a functionality for checking the functional unit of the cooling device or of the application units may be provided. For this purpose, it is possible to allow during operation an active response within a process model. Malfunctions can be established within the maintenance cycle.

(11) In this case, the complete water management can be incorporated, and the pump control can be performed via the calculated and set water quantities. In this way, only the mass quantity required for the cooling task is released by way of the pumps.

LIST OF REFERENCE SIGNS

(12) 1 Cooling group of the laminar cooling apparatus 2 Central inflow 3 Distributor tube 4 Application unit (cooling bar) 4.1 Application unit (cooling bar) 4.2 Application unit (cooling bar) 4.3 Application unit (cooling bar) 4.4 Application unit (cooling bar) 4.n Application unit (cooling bar) 5 Cooling nozzle 6 Volume flow-regulating valve 7 Throughflow measurement means 8 Closed loop controlled system 9 Valve F Conveying direction