改变燃尽风风量配比对660MW超超临界前后对冲煤粉锅炉炉内燃烧影响的数值模拟研究

Numerical Simulation Study on Impact of Changing Burnt-out Air Volume Proportion on Furnace Combustion of 660 MW Supercritical Before and After Hedge Pulverized Coal-fired Boiler

利用ANSYS FLUENT14.0软件对某电厂660 MW超超临界旋流燃烧煤粉锅炉变燃尽风风量对NOx生成规律的影响进行数值模拟研究,数值模拟的结果与现场实际情况吻合比较好,验证了数值模拟结果的有效性,主要结论如下:总二次风量不变,改变燃尽风风量对炉内温度场分布的影响较大,对炉膛出口烟温影响较小;改变燃尽风风量对炉内NOx浓度影响较大;随着燃尽风风量的增加,炉膛出口CO的平均体积分数逐渐增加,炉内燃烧化学不完全热损失逐渐增大,锅炉热效率降低;在综合考虑锅炉的安全性、热效率和NOx排放量3个因素时,燃尽风风量的比例应该控制在23%～30%内。

By using ANSYS FLUENT 14. 0 software, this paper proceeds numerical simulation study on impact of changing burnt-out air volume proportion on NOx generation law of 660 MW supercritical vortex pulverized coal combustion boiler of some power plant. Result of numerical simulation is coincided with locale physical truth which verifies effectiveness of nu- merical simulation. Main conclusions are as follows： when total secondary air volume is invariant, change of burnt-out air volume may have great impact on furnace temperature field distribution while less impact on hearth exit gas temperature; change of burnt-out air volume may have great impact on furnace NOx density; with increase of burnt-out air volume, the average volume fraction of hearth exit CO may gradually increase, furnace combustion chemical incomplete heat loss may gradually enlarge while thermal efficiency of the boiler may reduce; when comprehensively considering safety, thermal efficiency and NOx discharge value of the boiler, proportion of burnt-out air volume should be controlled at 23% ~30%.