On-line Monitoring And Control Of Cooling Temperature On Run-out Table Of Hot Strip Mill

Based on the product enhanced quality technical transformation project after rolling cooling system engineering project of Ansteel Co.Ltd the control technology and new technology of 2150 hot rolling ultra fast cooling system.The calculate model of cooling temperature after rolling,adaptive function of on-line monitoring and control system,feedforward control based on on-line monitoring system and feedback control system after cooing are studied.The developed hot strip on-line monitoring and control system has achieved good results.The main research contents and achievements of this paper are as follows:(1)The high precision model of cooling temperature control after rolling is established.The heat conduction equation is solved by the finite difference method.A new node partition method is proposed.The temperature calculation of the strip thickness is more accurate.The boundary conditions of the discrete heat conduction equation and the model of the thermal performance of the material are presented.(2)For the poor conditions of water vapor and fog in the cooling zone after rolling,the temperature of the cooling zone is difficult to measure.Based on temperature soft sensing technology,the on-line monitoring and controlling system of cooling temperature after hot rolling is developed,monitoring the real time state of strip in cooling zone after rolling.According to the on-line monitoring and control system,the adaptive optimization of the finite difference temperature model can be carried out.The optimization strategy is based on the finite difference temperature model,which has a profound significance for the development of the finite difference temperature model.(3)The influence of large velocity fluctuation on the cooling temperature control after rolling is observed.Based on the on-line monitoring and control system,the feed forward control strategy is proposed.The method can be calculated according to the temperature of the on-line monitoring temperature,thus the temperature deviation can be corrected in time.The positions of the re-point are presented,including the coarse and fine section.Thus,the speed fluctuation is corrected for two times and the temperature deviation is reduced to the minimum.(4)The control principle and the shortage of the feedback control method for the conventional PID feedback control method and the Smith predictor are deeply analyzed.A new type of feedback control strategy based on self-learning in coil is proposed.The feedback control strategy is also suitable for the ultra fast cooling section.Therefore,this method can improve the accuracy of the calculation of the temperature of the coiling temperature and improve the accuracy of the ultra fast cooling outlet temperature.(5)The on-line monitoring and controlling system for cooling temperature of hot rolled strip after rolling is applied to actual production.Production practice shows that,laminar cooling mode separately,CT precision within the range of 20 ? is higher than that before the system transformation;For ultra fast cooling temperature precision,Q345B is 95%,higher than 90%before.Pipeline steel X70 CT precision is 90%within the range of 40 ?,higher than 75%before.