Gas Mixing Process Intelligent Decoupling Control Algorithm And Its Application

In the iron and steel enterprise, some equipment such as blast furnace, coke ovenand converter oven will generate byproduct gas. The gas mixing process is to recyclethis byproduct gas which not only saves energy but also reduces environmentalpollution. It is an important link in the iron and steel production. The calorific valueand pressure's stability directly influences the gas quality, the life-time of ovens,producing environment and the iron's quality and quantities. Therefore, research ongas mixing process control is a vital significance for the iron and steel enterprise.The gas mixing process is a very complex industrial process. The features ofmulti-variable, strongly coupled, nonlinear, changeable parameters, and hard inmodeling are the major control challenges in the gas mixing process. Based onprofound researching on the characters and control difficulties of gas mixing process,this paper proposes an intelligent integrated decoupling control algorithm, whichincorporates decoupling control with fuzzy control, feedforward control and expertcontrol.At first, through analyzing the characteristics of gas mixing process singlevariable, adopt "rough adjustment" or "fine adjustment" fuzzy controller, and useexpert control algorithm for special working conditions. At the same time,compensate big perturbation by using the feedforward expert control algorithm. Thenfuzzy decoupling control method is adopted to realize the decoupling ofmulti-variables of gas mixing process. Based on summarizing the experience ofoperating workers and analyzing the characters of gas mixing process and butterflyvalves, this paper designs fuzzy decoupling control method based on expert rules,similarly decompose the multi-variable process to single input, single output process,and hierarchically eliminate the coupling among each loop. Finally, butterfly valvecontroller is designed. Through analyzing the butterfly pai'allel and series relative gainmatrix, theoretical basis is created for the design of gas calorific value and pressuredecoupling control rules, the distribution of blast furnace valves control value andcoke oven valves control value to each two valves. Furthermore, butterfly valveexpert controller is developed to adapt to the characteristic of butterfly valve so as toenhance the control quality. The control algorithm is applied in two type gas mixing processes in some ironand steel company. The actual run result showed that, the control algorithm is simple,feasible, reliable, and easy to expand and strongly resisting, even when the controlledmember mathematical model is difficulty to determined, realized the stability of thecoke oven and blast furnace mixing gas calorific value and pressure, of the pressure ofmulti coke oven gas collectors. It has created great economic and social benefits;meanwhile, it also lessens the labor intensity. In a word, it provides an efficientmethod for the decoupling control in the gas mixing burning process.