The influence of distance between adjacent rings on the gas/particle flow characteristics of a conical rings concentrator

A phase Doppler anemometer system was used to study gas-particle flow characteristics of a conical rings concentrator for a centrally fuel-rich burner. The influences of distance between adjacent rings on the distribution of mean axial velocity, particle volume flux, particle number concentration, rich/lean air ratio, concentration ratio and resistance coefficient were obtained. In each cross-section, within the radius range from 0 to 35 mm, the particle axial volume flux for four distances was always far larger than at other radial positions. When x/D was larger than 1.5 and L was larger than 48 mm there was only a slight influence of distance on the concentration ratio. The resistance coefficient decreased with increasing distance and the larger the distance was, the more slowly the resistance coefficient decayed. In the five cross-sections from x/D = 0.1 to 1.5, RCR for the four distances were always greater than 2. This indicates that the centrally fuel-rich burner with a conical rings concentrator for four distances could achieve a stable flame. Although the length of the primary air duct is long enough and the primary air fan total head is limited, it is best to choose the larger distance.