Influence of the gas particle flow characteristics of a low-NOx swirl burner on the formation of high temperature corrosion

In order to figure out the reasons for high temperature corrosion on side water walls, experimental investigations have been conducted on a 600 MWe boiler. Samples collected from the side water walls were analyzed by XRD and SEM-EDS. The results revealed that the deposition of FeS and unoxidized fuel was responsible for the high temperature corrosion. Then the gas particle flow characteristic downstream of the HT-NR3 swirl burner was investigated using a three-component particle-dynamics anemometry (PDA) system. Velocities, particle concentrations and particle diameters were obtained. Results showed that there was an annular recirculation zone existing between the primary air and the secondary air. The mixing of the secondary air with the primary air downstream of the recirculation zone was very weak, so as the entrainment effect of the swirling outer secondary air on particles. Large particles tended to reach the water wall more easily. These gas particle flow characteristics strengthened the oxygen-deficient combustion for pulverized coal particles and increased the possibility of the deposition of FeS and unoxidized fuel. (C) 2014 Elsevier Ltd. All rights reserved.