700MW四角切圆锅炉低NOx燃烧的数值模拟  

Numerical Simulation of the Low NO_x Combustion of a 700 MW Tangentially-fired Boiler

作　　者：钟礼今 张殿平 田登峰 方庆艳[2] 

机构地区：[1]珠海发电厂,广东珠海519000 [2]华中科技大学煤燃烧国家重点实验室,湖北武汉430074

出　　处：《热能动力工程》2015年第1期118-123,169-170,共6页Journal of Engineering for Thermal Energy and Power

摘　　要：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。A numerical simulation was conducted of the in-furnace flow,combustion,heat transfer and pollutant emissions characteristics of a 700 MW tangential pulverized coal-fired boiler. The simulation results were in good agreement with the measuring values. Both the numerical simulation and practical operation results show that after the A-PM( advanced-pollution minimum) low NOxburners had been adopted and an in-depth air staged combustion modification has been preformed,the in-furnace air dynamic characteristics are good and the air flow will never directly sweep through the water wall and the main combustion zone will be just in its strong reduction atmosphere with a low oxygen and high CO concentration,thus prohibiting the formation of NO and reducing NO that had been produced in alarge amount. The NOxemissions from the boiler will drop conspicuously,declining 68. 8%,52. 9% and 56. 6% at a load of 100%,75% and 50% respectively. The temperature of the flue gases at the bottom of the tube platen will obviously increase and the main and reheat steam characteristics will improve considerably,thus the temperature will increase to the design value and the heat load of the wall surface of the water wall will be more uniform. Although the carbon content of flying ash and CO emissions concentration will increase,yet the temperature of the exhaust flue gases will decline by about 10 ℃ and the decrease in the heat loss of the exhaust flue gases will be greater than the sum of the mechanical and chemically incomplete combustion loss thus increased,therefore,the boiler efficiency willincrease.

关 键 词：煤粉 低NOX燃烧 深度空气分级 数值模拟 

分 类 号：TK227[动力工程及工程热物理—动力机械及工程]