The Boiler Temperature Control System, With Dahlin

This thesis has been carried out based on the annealing furnace temperature control loop redesign project of a domestic steel Mill.The annealing furnace is very important equipment in cold-roll steel sheets heat treatment process and used widespread in China.Temperature control in each heating phase will significantly impact steel sheets quality. When we facing today's economy crisis,an advanced temperature control will be great significance in steel metallurgy.Annealing furnace has some distinguishing feature like quick temperature rising,big deadtime.It uses burning mixing with gas and air to meet process requirements.Each phase have to take temperature overshoot into account,if overshoot has been mismatched,will cause furnace temperature control unstable and much higher defective rate. Even use normal PID algorithm for deadtime control loop,system can not kill overshoot and seriously affect the steel quality.Due to the annealing furnace long delay feature,I made modeling with simulation according to field experience,then determine system parameter and transfer function.This thesis select a famous algorithm, which was developed to be used in process with significant deadtime for annealing furnace.After simulate with Matlab,the system depict a good control quality.This thesis also discuss furnace temperature control system hardware and software deisgn.Especially uses a special IC which compatible with K-type thermocouple,and D/A chip which can output 4-20mA directly,these solution resolve a lot of issue,not only the accuracy issue,but also time saving,simplify circuit design and high stability of control system.Based on the deep analysis of annealing furnace characteristic, construct furnace temperature control system with Dahlin's algorithm, can be for reference to some extended in the matter of academy studies and application.