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对某350 MW煤粉锅炉的低氮燃烧改造方案进行分析,采用数值模拟方法研究了不同工况下气流的速度场、炉膛温度场和NOx排放质量浓度,并与实测结果进行了对比.结果表明:延长并调整旋流燃烧器二次风的扩锥可降低NOx的排放质量浓度;改变燃尽风喷口结构,增大燃尽风风量,使主燃区总体处于还原性气氛,既有利于NOx的还原,又能有效控制炉膛出口烟气温度,缓解屏底结焦状况;数值模拟结果与实测结果吻合较好.
A 350 MW pulverized coal fired boiler with low nitrogen combustion transformation program was analyzed and numerical simulation was used to study the airflow velocity field, furnace temperature field and NOx emission mass concentration under different operating conditions, and the results were compared with the measured results : Extending and adjusting the expansion cone of the secondary air of the swirl burner can reduce the mass concentration of NOx emission; and changing the structure of the air exhaust nozzle to increase the amount of the exhaust air to be burned so that the main combustion zone is generally in a reducing atmosphere, Reduction, but also can effectively control the flue gas temperature at the exit of the furnace and alleviate the coking on the screen. The numerical simulation is in good agreement with the measured results.