Research And Numerical Simulation On Structure Of Low NO_x Swirl Burner

With the implementation of the "New Environmental Protection Law" and other policies,energy saving and low nitrogen has become the main development direction of industrial burners.Using mechanical swirl combustion technology,the installation angle and rotating speed of blades are analyzed by numerical simulation.The effect of air equivalent ratio on combustion characteristics and NOX emission of gas burner.The purpose of this paper is to design and process 75 kW low NOX mechanical swirl burner.The burner uses LPG as fuel and external motor as rotating power.The motor drives rotating blade by deceleration gear.The installation angle of blade is30,45,60,90,respectively,and this burner uses liquefied petroleum gas(LPG)as fuel and external motor as rotating power.The rotating velocity of the blade is designed as0,200,400,600,800,1000 rad / min,and the air equivalent ratio is 0.8,0.9,1.0,1.1,1.2,1.3,1.4,1.5.In this paper,the combustion of the blade is numerically simulated by using ANSYS 16.0 software,and the results show that the air equivalent ratio is 0.8,0.9,1.0,1.1,1.2,1.3,1.4,1.5,respectively.The results show that:1.The circumferential vortex motion has obvious advantage in the stable temperature field.With the increase of blade installation angle,fuel combustion becomes fuller,in which the blade circumferential vortex motion with only 90 installation angle runs through the entire combustion chamber along the axis.The corresponding radial temperature and axial center temperature are the lowest,that is to say,The local high temperature in the main combustion zone is effectively reduced.2.The effect of radial swirl on NO concentration is greater than that of axial reflux on NO concentration.The existence of peak low temperature inside vortex nucleus plays an important role in reducing local high temperature.3.The combustion efficiency is based on the critical speed of 400rad/min,and only the blade Flake speed over 400rad/min will promote fuel and air mixing,conversely reduce combustion efficiency.4.Two vortices exist in the center of radial swirl with 400rad/min as critical speed and 400rad/min velocity as critical speed.At 0.72 m,the motion is approximately in accordance with the law of free vortex nucleus motion.The tangential velocity peak occurs at the boundary of the two vortex centers,while outside the 400rad/min rotational velocity,there is only one vortex in the center of the radial vortex,that is,the forced vortex.The tangential velocity peak occurs at the junction between the forced vortex and the free vortex nucleus,and the motion is in line with the circle.Vortex nucleus motion,forced vortex nucleus contains peak high temperature region and peak low temperatureregion,and vortex center is located in high temperature region.5.When the 90 installation angle blade is selected,the corresponding rotating speed is 800-1000 rad/min,and the air equivalent ratio is 1.3,the combustion efficiency can be achieved and the NO concentration at the outlet of the combustion chamber can be satisfied at the same time.At the same time,the temperature of the central axis of the combustion chamber is relatively balanced.