Numerical Simulation Of Optimization Of Burnout Characteristics For A Swirl-Opposed Firing Boiler

The opposed firing boiler have been widely used in China because of the advantages of better flame fullness and better coal adaptability.At present,there are many reports on the characteristics of flow,combustion,heat transfer and pollutant generation of this type of boiler.However,under the condition of significantly improving operational flexibility and commonly used non-design coal,it is of great significance to carry out combustion optimization research on this type of boiler and improve the combustion efficiency of pulverized coal,which is of great significance to energy saving and emission reduction and carbon emission reduction.In this paper,a 600 mw pulverized coal combustion boiler wall before and after the hedge to carry out the numerical simulation work,with the burner research to burnout burnout characteristics as the breakthrough point,explores the way of air distribution,vortex intensity and burner output influence on burnout characteristics,and to put forward the burner area below to fill the wind way to increase the rate of pulverized coal burning,provide guidance to hedge boiler combustion efficiency.Firstly,according to the actual structure and size of the boiler,the geometric model was established,the grid was divided,and the appropriate numerical simulation model was selected to simulate the reference working condition,and the rationality of the simulation results was verified.The pulverized coal burnout rate of each burner in the reference working condition is carefully analyzed.The results show that the pulverized coal burnout rate of the lower burner is lower than that of the middle burner and the upper burner,while for the same burner,the pulverized coal burnout rate of the middle burner is higher than that of the two burner.This is consistent with the data rule of field measurement,and further verifies the geometric model,grid and mathematical model used in this paper.Secondly,the variable air distribution mode,variable swirl intensity and variable burner output condition of the boiler are simulated.The results show that when the air distribution mode of the same layer burner is changed,the total burnout rate of pulverized coal will be increased when the air volume of the middle burner is appropriately reduced and the air volume of the two side burner is increased.When changing the swirl intensity of the burner,increasing the swirl intensity of the burner on both sides of the same layer can increase the total burnout rate of pulverized coal.The change of pulverized coal output of the same layer burner has little effect on the total burnout rate of pulverized coal.Finally,the mode of air supplement under the lower burner is proposed to improve the burnout rate of pulverized coal,and the optimization simulation of air supplement under multiple working conditions is carried out.The results show that the air supply mode at the bottom of the lower burner can effectively lift the trajectory of pulverized coal particles from the lower burner,form a relatively ideal effect of flow hedge,and effectively improve the total burnout rate of pulverized coal.The side air supply mode of cold ash hopper can better reduce the number of pulverized coal particles falling into the area of cold ash hopper of the lower burner.When the Angle between the air supply Angle and the horizontal direction is 20°～33°,the effect is better,and the total burnout rate of pulverized coal is higher.However,the air supply at the bottom of the cold ash hopper has no obvious lifting effect on the pulverized coal particles from the lower burner,and the total burnout rate of pulverized coal decreases to some extent.