论文部分内容阅读
对一台700 MW四角切圆煤粉锅炉低NOx燃烧改造前后开展了多工况炉内流动、燃烧、传热与污染物排放特性的数值模拟,模拟结果与测量值符合良好。数值模拟与实际运行结果都表明:采用M-PM低NOx燃烧器并进行深度空气分级燃烧改造后,炉内空气动力特性良好,气流不会直接冲刷水冷壁;主燃烧区处于低氧高CO浓度的强还原性气氛,可抑制NO生成并大量还原已生成NO,锅炉NOx排放显著降低,100%、75%和50%负荷下分别降低了68.8%、52.9%和56.6%;屏底烟气温度明显增加,主、再热汽温特性明显改善,温度升高达到设计值;水冷壁壁面热负荷更加均匀;尽管飞灰含碳量和CO排放浓度增加,但排烟温度降低了约10℃,排烟热损失降低大于机械和化学不完全燃烧损失增加之和,锅炉效率升高。
Before and after the low NOx combustion retrofit of a 700 MW tangentially pulverized coal fired boiler, the numerical simulation of the flow, combustion, heat transfer and pollutant discharge in a multi-working furnace was carried out. The simulation results are in good agreement with the measured values. Numerical simulation and actual operation results show that the aerodynamic characteristics of the furnace are good and the airflow does not directly scour the water wall after the M-PM low NOx burner is used and the deep-air staged combustion retrofits are carried out. The main combustion zone is under low oxygen and high CO concentration Of the strong reducing atmosphere can suppress the NO generation and a large number of reduction has been generated NO, the boiler NOx emissions decreased significantly, respectively, reduced by 68.8%, 52.9% and 56.6% under 100%, 75% and 50% load; The temperature of the main and reheat steam significantly improved, and the temperature reached the designed value. The heat load on the wall of the water wall was more uniform. The exhaust gas temperature was reduced by about 10 ℃ despite the increase of carbon content and CO emission concentration, The reduction in exhaust heat loss is greater than the sum of the increase in mechanical and chemical incomplete combustion losses and the boiler efficiency increases.