200MW四角切圆燃烧锅炉改造工况数值模拟

煤粉再燃是降低NOx排放的一项新技术。利用CFD软件平台，采用数值模拟方法对某电厂200MW四角切圆燃烧锅炉改造前后炉内燃烧状况进行研究。改造方案1采用空气分级，方案2在1基础上，增加细粉再燃。计算结果表明：改造后在最上面一层一次风喷口的高度区域，温度骤然下降，而CO浓度很高，形成一个相对低氧，低温的还原性气氛区域。再燃降低NOx48．9％左右。改造后煤粉燃尽率下降且燃尽所需时间也增加，降低了电厂的经济性。煤粉颗粒在炉内运动具有很大随机性，停留时间差异很大。平均而言，煤粉喷入高度越高，停留时间也越短。

NUMERICAL SIMULATION OF COMBUSTION PROCESS IN A 200MW TANGENTIALLY FIRED FURNACE TO STUDY FURNACE RECONSTRUCTION

Coal reburning is a new technique to reduce nitrogen oxides (NOx) emission. Numerical simulation of combustion process in a 200 MW tangentially fired furnace is performed on CFD (Computational Fluid Dynamics)software platform. Air staging technique is applied in reconstruction project 1 and coal reburning is applied in project 2. Results show that after furnace reconstruction, at 5.26m furnace height, temperature drops to a low lever and so does oxygen concentration but carbon monoxide concentration is the highest. Deoxidization zone is formed. Micronized coal reburning can reduce NOx emission up to 48.9%. Coal burnout ratio reduces after reconstruction that decreases furnace economy. Coal particle movements in furnace are random. Averagely, particles residence time is longer if they are injected from a higher height position.