Experimental Study On Flow Characteristics Of The 0.5MW Centrally Fuel Rich Burner

Centrally fuel rich burner is a new high efficiency, low NOx swirl burner. In this paper, it produced a model according to a centrally fuel rich burner of a 0.5MW thermal test stand in proportion 1:1, and studied the characteristics of single-phase and gas-solid phase flow of the model export by using IFA300 and PDA. The parameters of single-phase and gas-solid phase flow of the burner model was measured at different primary air ratio, inner secondary air rate, outer secondary air blade angle and inner secondary air blade angle.It is found that the origin of recirculation region move backward, the radial size and axial length of recirculation zone decreased with the primary air rate increases. With higher primary air rate, particles are more concentrated. The average size of particle is larger in primary air control areas, the relatively density of particle is smaller and the particle volume flow is larger in the recirculation region. Excessive primary air rate will reduce the combustion efficiency and is not conducive to suppress NOx formation.The origin of recirculation region move forward, the radial size and axial length of recirculation zone increased with the inner secondary air rate increases. With higher inner secondary air rate,the particles concentrated area expansion along radial direction, the particle volume flow is more uniform distributed along the radial, which is conducive to stable combustion and improved combustion efficiency. But the excessive inner secondary air rate may cause burner slagging and coal fragmentation and is not conducive to suppress NOx formation.The resistance of outer secondary air blade will appear the phenomenon that decreased after increasing with the outer secondary air blade angle increases. It lead to that the intensity of recirculation region reduce and the radial size and axial length of recirculation region decreased after increasing. The blade angle of outer secondary air is too large or too small will cause the relative concentration of particles near the axis region and is lack of coal powder concentration in the recirculation region. It is not conducive to stable combustion and suppress NOx The intensity of recirculation region increases and the radial size and axial length of recirculation region increases with the inner secondary air blade angle increases. The relatively density of particle and particle volume flow is uniform distributed first then more concentrated in the recirculation region. When the angle of inner secondary air is 60°,it could form a recirculation region that radial size and axial length of recirculation region is relatively large, and particle distribution relatively uniform. It helps to improve combustion efficiency and stability and suppress NOx formation.