Research On Optimal Control Of Blast Furnace Pulverized Coal Injection Based On Flame Temperature

The blast furnace is the largest closed reaction vessel in industrial production,and its smelting process has the characteristics of strong coupling,non-linearity,large time delay and multi-phase.Its energy consumption and pollution emissions account for 70% of the total steel industry.In order to achieve the development of blast furnace smelting process towards energy saving,low consumption and automation,it is imperative to study the optimal control of blast furnace operation.At present,replacing part of coke with pulverized coal injection is the most effective way to realize energy saving and consumption reduction of blast furnace.The timing and quantity of increasing coal and reducing coke are still controlled by the furnace director artificially,which is blind and rough in operation and improper operation can bring huge economic losses.In view of the above problems,this paper focuses on the blast furnace optimization control based on the flame temperature in the raceway zone to carry out the following work:(1)During the smelting process of blast furnace,the tuyere is the only peephole that can observe the state of the furnace in real time.The real-time observation of the raceway determines the pulverized coal digestibility is the necessary condition for improving the coal injection ratio;the accurate detection of the temperature of the raceway is the key to ensure the smooth operation of the blast furnace.In view of the non-contact measurement of the blast high-temperature furnace tuyere with CCD image sensor,due to the complex interference of the industrial site,the collected tuyere radiation image often has a lot of noise.This paper proposes a filtering algorithm based on wavelet transform and BM3 D algorithm,which can effectively suppress the Gaussian noise while removing the fringe noise.For large spots and halos existing in high temperature radiation images,the watershed algorithm is used to segment the radiation image and to accurately identify the target of the radiator to be measured.Finally,the temperature of the raceway is obtained by colorimetric temperature measurement.(2)Aiming at the problem of blindness,roughness and lag in the increment and decreaseof coal injection,this paper establishes an evaluation model of pulverized coal digestibility in tuyere raceway to judge the pulverized coal combustion status in the raceway in real time,which provides a basis for decision-making of increasing coal and reducing coke and also improving the pulverized coal injection ratio.A new fuzzy comprehensive evaluation model based on the theoretical and objective evidence fusion is proposed,which,integrating the theoretical combustion temperature,pulverized coal combustion rate,temperature gradient,activity and uniformity of combustion zone.The multi-level fuzzy comprehensive evaluation method was used to evaluate the pulverized coal digestibility of the raceway from top to bottom and step by step.The evaluation model is applied to analyze the off-line data of the actual blast furnace,and the evaluation results are in line with the actual operation data analysis.(3)For the characteristics of non-linearity,strong coupling and large time lag in blast furnace smelting.While ensuring the high digestibility of pulverized coal in the raceway,the coal injection feed-forward compensation is realized through expert decision-making and predictive control.In order to ensure the balance of energy flow and material flow,coke is replaced by replacement ratio rule.The above measures can solve the problem of large time delay of blast furnace,realize the optimization control research of blast furnace operation,and achieve the purpose of energy saving and consumption reduction.The experimental research and expert analysis prove that the scheme can ensure the balance of energy flow and material flow in the process of blast furnace ironmaking,and ensure the smooth operation of the whole blast furnace.The work in this paper can effectively optimize the operation of blast furnace smelting process,save smelting costs and energy consumption,improve the utilization of resources,and guide production to achieve the best results.It will help promote the development of blast furnace smelting process towards energy saving,low consumption and automation.