Study On Coordinative Optimal Methods Of Casting Speed And Secondary Cooling Flow Rate Of Slab Continuous Caster

Continuous casting is one of the cores of the iron and steel production process and is also the intermediate link of steelmaking and rolling. Due to the uncertainties in actual production, the production scheduling plan need to be changed, which results in the casting speed adjustments for the timely requests of the scheduling change and the cooling flow rate adjustment for the quality of the slab. At present, the control and optimization methods of continuous casting are mainly static control, parameter optimization of static control and dynamic control, but few literatures on the real-time dynamic optimization of water and on optimization of casting speed adjustment for time disturbance, less on coordinative optimization of casting speed and cooling flow rate. In this thesis the optimization of the casting speed adjustment, real-time dynamic optimization of cooling flow rate and coordinative optimization of casting speed and cooling flow rate are studied.This study firstly describes and analyzes the casting production process and its operations, summaries and points out the insufficiency in the present research of casting speed and secondary cooling water control and optimization, and carries out works as follows:(1)The problem of coordinative optimization of the casting speed and secondary cooling flow rate are described, and the research difficulties and the method strategies are introduced. For the existence of a large number of time-consuming calculation in the optimization of casting speed and secondary cooling water, a simplification is done to the life circle model through ending the life of some life units appropriately.(2)Based on the simplified life circle model and the one-dimensional heat transfer model, a slab dynamic model is established and the its numerical solution is also given. Adopting the slab dynamic model, the method of real-time optimization setting of secondary cooling flow rate is proposed, based on the state transition of the slab temperature along the ideal state trajectory. Then the real-time optimization setting of the secondary cooling flow rate is proposed and the method of optimization setting of casting speed adjustment curve is also proposed through the coordination of the proposed state deviation index during the water optimization and the transition area index of the casting speed adjustment curve. The off-line optimization strategy of the coordinative optimization of casting speed and secondary cooling flow rate is proposed through the integration of real-time dynamical optimization setting of secondary cooling flow rate and the optimization setting of casting speed adjustment curve. Due to the expensive computation time of the off-line optimization, an on-line optimization strategy of coordinative optimization is proposed based on the the casting speed adjustment curves from the off-line calculation.(3)Using the data of a certain steel grade and a certain caster in a steel making plant, a series of simulation experiments are done for the real-time dynamic setting of secondary cooling flow rate. Then two optimization experiments are designed, one is the optimization of casting speed and secondary cooling flow rate respectively and the other is the optimization of casting speed and secondary cooling flow rate coordinately. The optimization results are compared and discussed. Furthermore, the proposed methods are compared with the method from the steel making plant. All the results demonstrate the effective of the proposed methods.