Research On Optimal Control Of Blast Furnace Pulverized Coal Injection Based On Distributed Fuzzy Model

The blast furnace is the most energy-consuming high temperature closed reaction vessel in the industrial production at the present stage.Its ironmaking process has the characteristics of large time delay and strong coupling,which accounts for nearly 70% of the energy consumption in the whole steel industry.Therefore,in order to realize the development of low energy consumption and intelligence of blast furnace,it is imperative to optimize the control of blast furnace smelting process.Replacing coke with pulverized coal(PC)is the most commonly used means of energy saving and emission reduction in blast furnace smelting.Considering that the timing and the total amount of pulverized coal injection(PCI)are still controlled by the blast furnace operator,and the operation control mode is relatively extensive,it is easy to cause the problem of poor smelting effect or even abnormal furnace condition due to the non-standard operation,which leads to serious safety accidents.Combined with the above background and combined with the specific operation data of blast furnace,this thesis adopted the intelligent control method to study the collaborative optimization control of blast furnace PCI,and carried out the following research work:In the process of blast furnace ironmaking,the energy conservation and emission reduction target was realized by increasing PCI and decreasing coke.Aiming at the problems of subjectivity,roughness and hysteresis in the manual operation mode,which was difficult to increase PCI and decrease coke,the upper and lower synergistic optimization control method was adopted.On one hand,the thermal balance of high temperature region was maintained by reducing the amount of coke accordingly in advance in the upper part.On the other hand,the high digestibility of PC in the lower part was ensured by oxygen-enriched air blast,in order to guarantee PC sufficient combustion in the raceway of tuyeres.Furthermore,from the perspective of control,the process of increasing PCI and decreasing coke was formulated,and the stability control problem of temperature of hot metal was transformed into which in the tuyere raceway.And then,the synergistic optimization control strategy by increasing PCI and decreasing coke and the stable control strategy of temperature in the raceway of tuyeres,which was affected by coke and PC with different lag time,were put forward.First,the T-S fuzzy model of PC combustion system was established with the divided maximum lag interval of PCI,which was identified,and T-S fuzzy sub-models were built in different lag time sub-intervals.Then,the state feedback controller was designed based on the principle of parallel distributed compensation(PDC),and sufficient conditions for the stability of the system was solved based on the Lyapunov stability theory and linear matrix inequality(LMI)method.The simulation experiment is illustrated the effectiveness of the model and the state feedback stabilization controller.Based on the above principles and methods,a collaborative optimization control scheme of blast furnace coal injection based on distributed fuzzy model was proposed.Theoretical derivation and simulation experiments show that the scheme can ensure the stability of molten iron temperature,and it has practical significance to achieve the goal of energy saving and emission reduction,cost reduction and efficiency improvement during blast furnace operation.