Modeling And Simulation And Control Of Laminar Cooling System For Hot Strip Mill

As a important way of the controlled cooling of hot rolled strip, Laminar cooling iswidely used in domestic hot-rolled plant.The control of cooling process temperature andthe control of coiling temperature will directly affect organizational performance andmechanical properties of the strip. So it has important practical significance for analysisand research of the system of laminar cooling for hot strip mill.This thesis takes thelaminar cooling system of2250Hot Mill of Wuhan Iron and Steel Group for background,the problems are considered which include dynamic temperature changes are ignored, andthe temperature gradient of the strip thickness is considered less in most model, and theresult of open-loop control is not satisfactory.Then a deep research is addressed for how toraise the accuracy of model track forecast and cooling temperature control of the hot rolledstrip. The contents and results are as follows:This thesis analyzes WISCO2250device process characteristics and strip coolingmechanism. Afterwards, the modeling method of strip cooling is determined: Athermodynamic temperature submodel is established according to strip external heattransfer mechanism, and a phase transformation kinetic temperature submodel is obtainedaccording to the phase transition mechanism.In the end,coupling relationship between twosubmodels is calculated by using iterative method.The main thermo-physical parameters of the cooling process strip are determinedwith reference to the physical parameters of typical steel,and the water-cooled heattransfer coefficient is calculated by using the linear regression method.Then offlinesimulation is conductedon the basis of the strip cooling temperature model. From this base,the relations are analyzedwhich phase change and water density and strip thickness andother factors contribute to the impact of the cooling model.At the same time, coolingmodel is validatedaccording to acquisition actual production data.A method to calculate optimal operating point of strip cooling process temperaturecontrol is proposed,which is applied to the design of the strip cooling control strategy. Onthe basis of large inertia and nonlinear and strong coupling of strip cooling process, stripcooling control strategiesaredesigned. They include preset-feedforward control and feedback-adaptive control, which the former is the primary method and the latter is theauxiliary method. At last, it confirms a conclusion through simulation results that theabove control method iseffective.