Numerical Simulation of OFA Effect on the Three-Dimensional Flow Field in Supercritical W-Shaped Flame Boiler

Supercritical W-flame boiler opens up a new way for improving power generation efficiency with low-volatile poor-quality anthracite coal, owing to its good characteristics of high thermal efficiency, environmental and energy-saving. The numerical simulation of the formation of three-dimensional W-shaped flow field of a 600MW supercritical W-shaped flame boiler was implemented by software fluent 6.3. The effect of over fire air (OFA) on flow field in the furnace was also studied. The results indicate that the formation of two pairs of double-vortexes flow structure in the furnace can enhance the heat transfer and mass transfer of pulverized coal flow. The vortexes can also increase the residence time of pulverized coal particle in the combustion chamber and be in favor of the burnout of pulverized coal. The structure of OFA on the arch can effectively reduce the erosion effect of the flue gas of pulverized coal on the throat area, the front wall and the rear wall. The structure of OFA also is good at avoiding slagging. The flow field will not be best if the ratio of OFA is too large or too small, an optimal ratio of air distribution exists for a W-shaped flame boiler. The study results have great significance for the optimization design and improving the efficiency of pulverized coal combustion of supercritical W-shaped flame boiler.