Numerical Study Of Combustion Process Of600MW Supercritical W Flame Boiler

Slit type burner is one of the most common burners in W flame boiler. In thispaper, taking the first600MW supercritical W flame boiler domestically designed andmanufactured by China as an example, using FLUENT software, the combustionprocess in the furnace is calculated by numerical simulation. Firstly, the combustioncharacteristic in furnace under basic conditions is researched in detail, and theaccuracy of the selected model in numerical simulation is verified. Secondly, thevelocity field, temperature field, CO concentration field, O2concentration field andNO concentration distributions in furnace under different load, different coal quality,different second air rate under arch and different air distribution deviation are studiedrespectively. Then combustion characteristics under various conditions are obtainedin detail.Research shows that the symmetry of velocity field and temperature field infurnace is good under two loads including100%and50%, the temperature field andvelocity field under75%load have a significant deviation, and the flame center under50%load is shifted downward obviously. When the load is75%, the temperature ofupper furnace is too high, the effective burnout time of pulverized coal reduces, thecarbon content of fly ash increases, the spray de-superheating water flow increases,which causes easily super-heater over-temperature and tube burst. When the load is50%, the flame center is shifted downward obviously, temperature gradient in ashhopper is too large, which leads to slag and tube explosion easily. When the load isfull, CO concentration is higher at upper furnace and burner zone, the probability ofregional slag is increased at these zones. So improving operation oxygen is suggestedto prevent regional slag caused by anoxia at water wall of upper furnace and burnerzone. In short, the change of coal characteristic and air distribution modes will causecombustion pulsation in furnace, and that will affect flame center position and the undershoot depth of arch lower air, even slag and tube explosion happens.