Study On Control System Of Flame Characteristics Of Pulverized Coal Burner For Aggregate Drying

The effect of aggregate drying is affected by the flame characteristics of pulverized coal burner.The flame characteristics control has the characteristics of nonlinear,large delay and coupling among variables.At present,the utilization rate of pulverized coal in aggregate drying burner is low,and the pollutant emission is not up to the standard.According to the requirements of aggregate drying process,how to effectively control the flame characteristics of pulverized coal burner,improve the automation degree of the system,effectively improve the utilization rate of pulverized coal and reduce the emission of pollutants while ensuring the drying effect of aggregate,has theoretical research significance and engineering application value.In this paper,LB2000 drying drum is used as the service object,and the swirl pulverized coal burner with stable combustion ring as the control object,the air supply,induced air volume and coal supply quantity as the input variables of the control system,and the output variables are flame length,flame temperature and NOx emission.The mathematical model of multi-input and multi-output control system is established by using tarzania algorithm;Based on the above,the double layer predictive control algorithm is introduced to control the flame characteristics of the pulverized coal burner;Finally,the flame characteristic control system of the pulverized coal burner is designed,and the simulation verification of the flame characteristic control algorithm is carried out by PLC software.The main contents of this paper are as follows:(1)Study on aggregate drying process and combustion flame characteristics of pulverized coal.Combined with the drying process of aggregate,the influence of different flame characteristics on the drying quality of aggregate is analyzed and the control variables of the pulverized coal burner control system for aggregate drying are preliminarily determined.(2)Build the mathematical model of aggregate drying pulverized coal burner control system.Three independent multi-input and single output subsystems are established with air supply volume,induced air volume and coal supply volume as input variables and flame length,flame temperature and NOx emission volume as output variables.By comparing the identification effect of least square method and bottle ascidian algorithm on unknown parameters in mathematical model,it is found that bottle ascidian algorithm has higher fitting accuracy for multi-input system.Based on this,three mathematical models of multi-input single output control system are constructed by using bottle ascidian algorithm.(3)Research on control algorithm of flame characteristics of pulverized coal burner for aggregate drying.The dynamic calculation layer mainly controls the overshoot of the system,improves the response speed,reduces the steady-state error,and mainly realizes the effective control of flame length,flame temperature and NOx emission;The steady-state optimization layer takes the air coal ratio as the constraint condition and the coal feed rate as the optimization objective.Through the steady-state optimization calculation,the minimum coal feed rate is obtained to achieve the optimal control of coal consumption.(4)Software design of flame characteristic control system for aggregate drying pulverized coal burner.On the basis of the above research content,according to the system control requirements,this paper puts forward the PLC selection scheme,allocates the hardware address,and uses PLC development software to design the control system software of pulverized coal burner flame characteristics,and finally completes the control of burner flame characteristics.Through the above study,the flame length can be controlled at 4000mm～4500mm,the flame temperature is controlled at 1710℃～1750℃,NOx emission is controlled at300g～650g,which meets the requirements of the drying process of aggregate.The research results of this paper lay a theoretical foundation for the development of the control system of the pulverized coal burner for aggregate drying,and provided a new idea for the effective control of a kind of pulverized coal combustion behavior.