Experimental Study On Gas-Prticle Flows Characteristics Of Double-Swirl Flow Burner

With the increasing stricter requirement of NOx emission all over the world, swirl burners with low NOx formation are more and more widely used in thermal power plants in China. However, a series of problems were arisen on the boilers adoping swirl burners, such as serious slagging in furnace, poor combustion stability at low load, and low adaptability of coal fineness. Thus, it is necessary to conduct study on gas-particle flows characteristics of low NOx swirl burners. In view of this, experiments were performed on Double-swirl Flow burner designed by Ishikawajima-Harima Heavy Industries Co., Ltd in Japanese. A three-dimensional PDA system was used to study gas-particle flow characteristics of DF burner with different secondary air fluxes and vane angles of inner and outer secondary air.When the mass flux of secondary air was 0.099kg/s, the recirculation zone could not form. There was a small ring recirculation zone with the mass flux of 0.142kg/s and 0.184kg/s. For three different mass fluxes of secondary air, two peak values of particle volume flux and relative number density of particles appeared in the secondary air flow zone and near-wall region. The diameter of particles near the chamber axis of burner was always less than that at other positions.The DF burner had a small ring recirculation zone near the burner nozzle with three different outer secondary air vane angles. The profiles of the particle volume flux had two peaks at sections of x/d=0.1-1.0, one was in the secondary air region and another was in the near-wall region. The relative number density of particles profiled similar to the particle volume flux, and the particles in the central region of burner were small.With two different inner secondary air vane angles, back flow occur in the near-wall region, and there was small ring recirculation zone near the burner nozzle. At sections of x/d=0.1-0.7, the particle volume flux had two peaks values while the relative number density had similar profiles. At sections of x/d=0.1-0.5, the diameter of particles near the chamber axis of burner was always less than that at other positions.The DF burner had similar distributions of axial RMS velocities, tangential RMS velocities and radial RMS velocities with different secondary air mass flux, inner and outer secondary air vane angles. Compared with the axial and radial velocities, the tangential velocities attenuated more quickly, and the tangential fluctuation velocities were lower.