Operation of a cooling unit with a minimal working pressure

Abstract

A liquid coolant ( 6 ) is fed into a header line ( 4 ) by means of a pump assembly ( 5 ). Branch lines ( 9 a to 9 d ), in which control valves ( 11 a to 11 d ) are arranged, branch off from the header line ( 4 ) to application units ( 10 a to 10 d ). The coolant ( 6 ) is applied to a hot rolled material ( 2 ) made of metal by means of the application units ( 10 a to 10 d ), and the rolled material ( 2 ) is thus cooled. For limit modulation values (kLim) of the control valves ( 11 a to 11 d ), a control unit ( 12 ) of the cooling unit ( 3 ) uses setpoint flows (Ka* to Kd) of the application units ( 10 a to 10 d ) to determine individual working pressures (pAa to pAd) which must prevail in the header line ( 4 ) for the setpoint flows(Ka* to Kd*) to flow in the branch lines ( 9 a to 9 d ).

1 . An operating method for a cooling unit for cooling a hot rolled material made of metal,
 wherein the cooling unit has a header line, into which a liquid coolant is fed by means of a pump assembly and from which a plurality of branch lines branch off to application units,   wherein the pump assembly has a number of pumps, a control valve is arranged in each of the branch lines, and the coolant is applied to the rolled material by means of at least some of the application units,   wherein setpoint flows which are to be fed to the application units are communicated to a control unit of the cooling unit,   wherein the control unit actuates the pump assembly in accordance with a final actuation state and the control valves in accordance with actuation values,   the method comprising:   determining the final actuation state of the pump assembly and the actuation values of the control valves by determining with the control unit a respective individual working pressure for the control valves for a respective limit modulation value of the respective control valve, which working pressure must prevail in the header line so that the respective setpoint flow flows in the respective branch line,   determining with the control unit a provisional actuation state of the pump assembly, with the result that a total flow of coolant which corresponds to the sum of the setpoint flows is fed to the header line by means of the pump assembly, and at the same time a provisional working pressure which is at least as high as the highest of the individual working pressures prevails in the header line,   determining with the control unit the final actuation state of the pump assembly in such a way, using the provisional actuation state of the pump assembly, that the total flow of coolant is fed to the header line by means of the pump assembly and, at the same time, a final working pressure prevails in the header line, and   determining with the control unit the actuation values of the control valves in such a way, using the final working pressure, that the respective setpoint flow flows in the respective branch line.   
     
     
         2 . The operating method as claimed in  claim 1 , wherein
 the limit modulation values of the control valves are the maximum modulation values of the control valves or lie in the vicinity of the maximum modulation values of the control valves.   
     
     
         3 . The operating method as claimed in  claim 1 , wherein, 
 as part of the determination of the provisional actuation state, the control unit takes into account secondary conditions relating to the pump assembly.   
     
     
         4 . The operating method as claimed in  claim 1 , wherein, 
 as part of the determination of the provisional actuation state, the control unit takes into account secondary conditions relating to the control valves.   
     
     
         5 . The operating method as claimed in  claim 1 , wherein,
 as part of the determination of the final actuation state of the pump assembly, the control unit additionally takes into account at least one previous final actuation state of the pump assembly and/or at least one provisional actuation state of the pump assembly which is expected in the future.   
     
     
         6 . A computer program which comprises machine code which resides on a non-transitory computer-readable medium and can be executed by a control unit of a cooling unit for cooling a hot rolled material made of metal, wherein the execution of the machine code by the control unit causes the control unit to operate the cooling unit in accordance with an operating method as claimed in  claim 1 . 
     
     
         7 . A control unit of a cooling unit for cooling a hot rolled material made of metal, wherein the control unit is configured to operate the cooling unit in accordance with an operating method as claimed in  claim 1 . 
     
     
         8 . A cooling unit for cooling a hot rolled material made of metal,
 wherein the cooling unit has a header line, a pump assembly and a plurality of application units,   wherein a liquid coolant is applied to the rolled material by means of at least some of the application units,   wherein the application units are connected to the header line via a respective branch line,   wherein the pump assembly has a number of pumps, by means of which the liquid coolant is fed into the header line,   wherein a control valve is arranged in each of the branch lines,   wherein the cooling unit has a control unit configured to operate the cooling unit in accordance with an operating method as claimed in  claim 1 .