Cooling control system for continuous casting of metal

Abstract

Maintaining the shell surface temperature profile under transient conditions by spray water cooling in continuous casting of steel is often desired to reduce occurrence of surface cracks. For this purpose, a real-time spray-cooling control system is provided that includes one or more of: a virtual sensor for accurate estimation/prediction of shell surface temperature, control algorithm and data checking subroutines for robust temperature control, server and client programs for communicating between these software components and the caster, and a real-time monitor to display the predicted shell surface temperature profiles, water flow rates, and operating data, among other things.

1 . A method, comprising:
 supplying molten metal to a continuous casting mold;   as the molten metal solidifies in the mold, directing a metallic strand received from the mold along a cooling pathway;   from time to time, taking measurement representative of heat transfer through the mold as the metallic strand advances from the mold;   providing a plurality of different cooling fluid discharge devices at different positions along the pathway to provide a plurality of different strand cooling zones;   for each one of the different strand cooling zones, adjusting a respective zone estimate representative of strand temperature in response to a change in the measurements; and   for each one of the cooling fluid discharge devices, regulating operation as a function of the respective zone estimate and a respective target value.   
   
   
       2 . The method of  claim 1 , which includes flowing a coolant through the mold and wherein the measurement correspond to a change in at least one of temperature of the coolant and flow rate of the coolant. 
   
   
       3 . The method of  claim 2 , which includes obtaining the measurement with at least one temperature sensor. 
   
   
       4 . The method of  claim 1 , wherein the adjusting of the respective zone estimate is further determined as a function of casting speed. 
   
   
       5 . The method of  claim 1 , wherein the adjusting of the respective zone estimate is further determined as a function of temperature of the molten metal that is supplied to the mold. 
   
   
       6 . The method of  claim 1 , wherein the strand moves along the pathway at least three meters per minute. 
   
   
       7 . The method of  claim 1 , wherein the strand has a minimum cross sectional dimension of no more than 100 millimeters. 
   
   
       8 . The method of  claim 1 , which includes:
 flowing a coolant through the mold;   determining a strand temperature profile from a number of virtual sensors;   defining each of the virtual sensors as a function of inlet and outlet temperatures of the coolant, flow rate of the coolant, and casting speed; and   determining the respective zone estimate from the strand temperature profile.   
   
   
       9 . An apparatus, comprising:
 a source of molten metal;   a continuous casting mold structured to receive the molten metal from the source   a number of rolls to withdraw a metallic strand along a cooling pathway from the mold;   a plurality of different cooling fluid discharge devices at different positions along the pathway to provide a plurality of different strand cooling zones;   one or more sensors providing a signal representative of heat transfer of the mold;   a processing device operatively coupled to the cooling fluid discharge devices and the sensors, the processing device being responsive to the signal to execute operating logic to determine a plurality of strand temperature estimates as a function of the heat transfer in correspondence to the different cooling zones and generate a plurality of cooling fluid discharge device control signals each as a function of a corresponding one of the estimates and a corresponding one of a number of zone target values; and   wherein the cooling fluid discharge devices are each responsive to a respective one of the discharge device control signals to regulate fluid discharge therefrom.   
   
   
       10 . The apparatus of  claim 9 , wherein the processing device includes means for generating the control signals as a function of a chemical composition of the strand. 
   
   
       11 . The apparatus of  claim 9 , which includes flowing a coolant through the mold, and the sensors detect inlet temperature of the coolant, outlet temperature of the coolant, and flow rate of the coolant. 
   
   
       12 . The apparatus of  claim 11 , further comprising:
 a first one of the sensors to determine temperature of the molten metal supplied to the mold;   a second one of the sensors to determine temperature of the strand from the mold; and   wherein the processing device includes means for determining the estimates as a function of the heat transfer.   
   
   
       13 . The apparatus of  claim 12 , further comprising means for determining casting speed and the estimates each as a function of the casting speed. 
   
   
       14 . The apparatus of  claim 12 , wherein the operating logic defines a closed-loop, feedback control for each of the zones. 
   
   
       15 . A method, comprising:
 supplying molten metal to a continuous casting mold;   as the molten metal solidifies in the mold, directing a metallic strand received from the mold along a cooling pathway, the strand including an outer cooling shell with a first shell side opposite a second side;   providing a plurality of different cooling fluid discharge devices at different positions along the pathway to provide a plurality of different strand cooling zones;   modeling temperature of the strand for the first side and the second side at each of a number of different points along the pathway;   estimating a first shell thickness profile along the pathway for the first side from the modeling and a second shell thickness profile along the pathway for the second side as a function of the values; and   in response to a difference in the first shell thickness profile and the second shell thickness profile, adjusting operation of one or more of the cooling fluid discharge devices.   
   
   
       16 . The method of  claim 15 , which includes flowing a coolant through the mold and the modeling of the temperature of the strand is performed as a function of heat transfer measured in the mold based on an inlet temperature of a mold coolant, an outlet temperature of the mold coolant and a flow rate of the mold coolant. 
   
   
       17 . The method of  claim 15 , which includes moving the strand along the pathway at least three meters per minute. 
   
   
       18 . The method of  claim 15 , wherein the strand has a cross sectional dimension of no more than 50 millimeters. 
   
   
       19 . The method of  claim 15 , which includes displaying a representation of the first shell thickness profile. the second shell thickness profile, and the metallurgical length. 
   
   
       20 . A method, comprising:
 supplying molten metal to a continuous casting mold;   as the molten metal solidifies in the mold, directing a metallic strand received from the mold along a cooling pathway;   operating a plurality of different cooling fluid discharge devices at different positions along the pathway to provide a plurality of different strand cooling zones;   estimating a temperature profile for the strand; and   regulating operation of each of the different cooling fluid discharge devices in accordance with a respective one of a corresponding number of closed-loop, feedback controllers as a function of the temperature profile.   
   
   
       21 . The method of  claim 20 , which includes accounting for one or more constraints of the discharge devices during the regulating of the operation. 
   
   
       22 . The method of  claim 21 , wherein the accounting for the one or more constraints includes anti-windup processing for each of the controllers to address a cooling spray rate limitation. 
   
   
       22 . The method of  claim 20 , which includes moving the strand along the pathway at least three meters per minute and the strand has a minimum cross sectional dimension of no more than 100 millimeters. 
   
   
       23 . The method of  claim 20 , wherein the controllers are each of a proportional-integral type. 
   
   
       24 . The method of  claim 20 , wherein the estimating is performed as a function of heat transfer measured in the mold, wherein the measurement is based on an inlet temperature of a mold coolant, an outlet temperature of the mold coolant and a flow rate of the mold coolant. 
   
   
       25 . A method, comprising:
 supplying molten metal to a continuous casting mold;   as the molten metal solidifies in the mold, directing a metallic strand received from the mold along a cooling pathway, the strand including an outer cooling shell with a first shell side opposite a second side;   providing a plurality of different cooling fluid discharge devices at different positions along the pathway to provide a plurality of different strand cooling zones;   preparing strand temperature estimates along the first side and the second side at each of a number of points along the pathway;   regulating operation of each the cooling fluid discharge devices as a function of the strand temperature estimates; and   displaying a first profile of varying first side shell thickness relative to first side position along the pathway and a second profile of varying second side shell thickness relative to second side position along the pathway based on the strand temperature estimates.   
   
   
       26 . The method of  claim 25 , which includes displaying metallurgical length along with the first profile and the second profile. 
   
   
       27 . The method of  claim 25 , wherein the strand moves along the pathway at least three meters per minute. 
   
   
       28 . The method of  claim 25 , wherein the strand has a cross sectional dimension of no more than 100 millimeters. 
   
   
       29 . The method of  claim 25 , wherein the preparing of the strand temperature estimates is performed as a function of heat transfer measured in the mold. 
   
   
       30 . The method of  claim 25 , wherein the regulating of the operation of the cooling fluid devices is performed with a closed loop, feedback controller for each of the cooling fluid devices. 
   
   
       31 . A method, comprising:
 supplying molten metal to a continuous casting mold;   as the molten metal solidifies in the mold, directing a metallic strand received from the mold along a cooling pathway;   operating a plurality of different cooling fluid discharge devices at different positions along the pathway;   sensing temperature at a number of points along the strand with a plurality of sensors to provide sensed temperature data;   calibrating a virtual software sensor temperature profile estimation with the temperature data; and   regulating operation of each of the different cooling fluid discharge devices in accordance with the temperature profile estimation after the calibrating of the virtual software sensor.