A Rolling Optimization Method Of Reheating Furnace Temperature Setting Based On The Billet's Specifications

Reheating furnace is the main equipment of steel hot-rolling production process and also one of energy consumption meanwhile.On the precondition of satisfying reheating furnace's manufacturing technique and process constraints and ensuring the billets within the reheating furnace to fit with rolling technology and rhythm,reheating furnace temperature optimization is to reasonably set furnace temperature in each section of the reheating furnace and realize the minimization of oxidation loss and energy consumption in the production process of the furnace while optimize its operation,so as to improve the quality of products and reduce production cost.The working conditions,such as the billet's initial temperature,geometric dimensioning and category as well as rolling rhythm,is frequently changed during the production process of the reheating furnace.But this will give rise to uncertainty and dynamic property in the practical production process.On this occasion,the furnace temperature value of each section must be set through online rolling optimization according to the process of production-specification working condition switchover,so as to guarantee that the billet's tapping temperature distribution can meet the requirements in the technical process of production,improve the quality of products and reduce energy consumption.The existing literatures are generally about the discussion of furnace temperature optimization and control problems in one production condition,but rarely mention dynamic optimization of the temperature in the process of production condition switchover.However,the set values of furnace temperature are usually adjusted according to the production condition alternation with relying on human experience in the production field,which is hard to achieve dynamic optimization and adjustment of the control system and brings about production efficiency and product quality issues.Therefore,the problem that how to set the reheating furnace temperature in the condition of specification switchover,is of great significance for making full use of current resources and energy-saving and cost-reducing.This thesis has been firstly analyzed the process of reheating furnace temperature setting in the working condition of production specification switchover,described online rolling optimization of the set temperature values and established a relevant dynamic model.Secondly,a solution strategy for the rolling optimization of reheating furnace temperature setting values is suggested based on the generalized predictive control thought,in allusion to process characteristics,such as time-dependent nature,nonlinearity,great inertia and large lag of the reheating furnace's production system as well as a peculiarity that nonlinear dynamic characteristics of the reheating furnace temperature optimization model in the working condition of production specification switchover are hard to be resolved.Then,the rolling optimization of the reheating furnace temperature setting in the unchanged-specification working condition is studied.A generalized controlled object prediction model that involves the billet and reheating furnace is set up with adopting the way of system identification,where the set value of the reheating furnace temperature is regarded as input and the temperature of billet is seemed as output.A closed loop feedback correction structure is introduced to overcome model prediction errors of billet temperature generated by other uncertainties disturbing within the system.A rolling optimization algorithm of furnace temperature setting in the unchanged-specification working condition comes into being on the foundation of defining performance index of the heated-billet's temperature.On this basis,the production process of working condition switchover of the reheating furnace is analyzed and described,and the weighting-method performance index and reheating furnace operation constraint models under the situation of specification working condition switchover is employed.Rolling optimization strategy is utilized to optimize all the furnace temperature setting values corresponding to in-furnace billet.Taking the established reheating furnace process model within the reheating furnace simulation experiment system in the laboratory and field data as the base,simulation experiment is conducted for the problem of rolling optimization about the reheating furnace temperature setting value in the working condition of specification switchover through MATLAB.The experimental results show that the rolling optimization strategy and algorithm suggested in this thesis bring about high optimization quality and short optimization term to the furnace temperature setting values in working condition of specification switchover.Furthermore,the methods adopted by this thesis have stronger anti-interference and robustness,and provide method basis for optimizing the reheating furnace temperature setting values in the working condition of specification switchover in the actual production.