Investigation On Gas/Particle Phase Flow And Combustion Characteristic Of Single Cone Swirl Burner

Swirl burner is the key technology and research focus of industrial boiler to realize high efficiency and low nitrogen combustion of pulverized coal.In this paper,the cold modeling and pulverized coal combustion tests of single cone swirl burner are carried out to study gas-solid flow and combustion characteristics of fuel basic jet comparing with the reverse jet.Then the influence of the secondary air distribution way on the combustion characteristics also is studied.The final conclusions are as follows:(1)Compared with reverse jet primary air and pulverized coal,when fuel basic jet is adopted in single cone swirl burner,there is no recriculation phenomenon in the pre-combustion chamber,the mixing area of secondary and primary air is longer.And the particles distribution of“inner larger outer smaller,inner thick outer thin”was presented.The high temperature oxygen free and strong reducing atmosphere region was formed in the single cone pre-combustion chamber,the temperature peak value is low and change is small,the radius of oxygen free zone is large and CO concentration is high.The shape of turbulent diffusion flame outside single cone pre-combustion chamber is stable,the low flame brightness and flame stroke increases greatly.The results show that the ignition stability of pulverized coal decreases at initial stage of combustion.But the coupling of pulverized coal concentration field with temperature field and component field is reasonable.The ability of restraining NO_xgeneration and maintaining downstream flame shape is strong.(2)When the ratio of inner and outer secondary air is 1/2 and the swirl number of inner secondary air is 1.67,the temperature peak value in the high-temperature oxygen free and strong reducing atmosphere area and the temperature of wall air layer in the pre-combustion chamber are moderate.The radius of oxygen free zone is larger and the average CO concentration in the strong reducing atmosphere is higher.The flame length outside the pre-combustion chamber is longer and the outlet diameter and divergence angle are moderate.The results show that the ignition stability of pulverized coal at the initial stage of combustion is moderate,the ability of restraining NO_xgeneration and the increase of flame stroke are conducive to reducing NO_xcontent and improving pulverized coal combustion efficiency.