为了解煤泥、煤矸石等多元低热值煤掺烧下CFB锅炉污染物生成排放特性，以某电厂350 MW超临界CFB锅炉为研究对象，基于现场运行实测数据，研究了该锅炉在30%～99%负荷率下烟气SO2、NOx生成及粉尘排放随负荷变化的特性，并分析了锅炉运行负荷、平均床温、过量空气系数及流化风率等关键运行参数对其生成与排放水平的影响。试验结果表明，该机组在30%～99%全负荷条件下总排放口烟气污染物排放均能够满足超低排放标准；SO2、NOx排放浓度随锅炉负荷的降低基本呈现先降低后迅速升高的趋势，粉尘排放浓度随锅炉负荷的降低而降低；所研究关键运行参数中，锅炉床温对SO2、NOx生成与排放水平起主导作用；低负荷下锅炉平均床温较低、炉膛过量空气系数较大，SO2、NOx生成浓度偏高，且二者排放浓度与过量空气系数及流化风率基本呈正相关。综合考虑，应适当控制锅炉平均床温在800 ℃以上，过量空气系数应不高于1.3为宜；低负荷下可采取烟气再循环措施来降低烟气含氧量，同时维持物料正常流化。

To master the pollutant emission characteristics of a 350 MW supercritical CFB boiler under mixed combustion of multi-element low-calorific value coal including coal slime and coal gangue, taking a 350 MW supercritical CFB boiler of a power plant as the research object, and based on the measured data of on-site operation, the formation and emission characteristics of SO2, NOx and dust in flue gas were studied against the boiler load rate between 30% and 99%. Additionally, the key operated parameters including boiler operating load, average bed temperature, excess air coefficient and fluidizing air rate on its generation and emission level were investigated. The test results reveal that the flue gas pollutant emissions of the CFB unit can meet the emission standards within the load range of 30%-99% at total discharge outlet. The emission concentration of SO2, NOx basically decreases first and then increases rapidly with the decrease of boiler load. The concentration of dust emission decreases with the decrease of boiler load, and the dust emission concentration decreases with the reduction of boiler load. Among the key operating parameters studied, the boiler bed temperature plays a leading role in the emission level of SO2, NOx. The emission concentration of SO2 and NOx is higher with the lower average bed temperature and the larger excess air coefficient, and the emission concentration is basically positively correlated with the excess air coefficient and fluidization air rate. Considering comprehensively, it is recommended that the average bed temperature of the boiler should be properly controlled above 800 ℃, and the excess air coefficient should be stabilized less than 1.3. The way of flue gas recirculation can be used to reduce the oxygen concentration of the flue gas under low load on the basis of the maintaining the normal fluidization of the material.

0 引言

1 设备概况

   1.1 锅炉概况

   1.2 环保设施概况

   1.3 数据采集与分析

2 试验工况

3 试验结果与讨论

   3.1 SO2排放特性

   3.2 NOx排放特性

   3.3 粉尘排放特性

4 结论