350 MW循环流化床锅炉不同负荷下运行特性及污染物排放试验研究

Experimental Study on Operation Characteristics and Pollutant Emissions under Different Loads in a 350MW Circulating Fluidized Bed Boiler

为满足电网深度调峰及超低排放的需求,超临界循环流化床锅炉不同负荷运行性能及污染物排放特性研究具有重要意义。针对某350MW超临界CFB锅炉,现场测试100%BRL、75%BRL及50%BRL负荷下机组排烟温度及烟气成分,获得锅炉不同负荷下运行性能并进行能效分析;通过调整炉内脱硫剂投入量,分析机组运行参数对SO2及NO_(x)等污染物排放的影响。研究结果表明:随锅炉负荷降低,CFB锅炉效率不断下降,100%BRL负荷时,各项热损失中排烟热损失占比最大,其次是灰渣未燃碳造成的热损失;75%BRL及50%BRL负荷下,各项热损失中灰渣未燃碳造成的热损失占比最大。炉内脱硫剂的投入可显著降低SO2排放,同时可影响炉内NO_(x)生成。随炉内脱硫剂投入量增加,SO2排放浓度快速降低。石灰石给料机频率由5.6 Hz升高至13.5 Hz,吸收塔进口SO2浓度由360.4 mg/m^(3)降至6.9 mg/m^(3),同时,炉内脱硫剂的投入可促进HCN及NH3等中间产物发生化学反应,生成更多的NO_(x),锅炉运行过程中,应合理选择炉内脱硫剂投入量。研究结果可为350MW CFB锅炉低负荷运行性能优化及降低污染物排放提供指导。

To meet the needs of deep peak regulation and ultra⁃low emissions of power grid,it is of great significance to study the operating performance under different loads and pollutant emission characteristics of supercritical circulating fluidized bed(CFB)boiler.In light of a 350MW supercritical CFB boiler,the exhaust temperature and flue gas composition of the unit under the loads of 100%BRL、75%BRL and 50%BRL were tested in the field,the boiler operation performance under different loads was obtained and the energy efficiency analysis was conducted.By adjusting the amount of desulfurizer in the furnace,the effects of operating parameters on the emission of pollutants such as SO2 and NO_(x)were analyzed.The results show that the efficiency of CFB boiler decreases as the boiler load decreases.The proportion of exhaust heat loss is the largest,followed by the heat loss caused by unburned carbon of ash slag under 100%BRL load.While under 75%BRL and 50%BRL load,the heat loss caused by unburned carbon of ash and slag accounted for the largest proportion of all heat losses.The input of desulfu⁃rizer in the furnace can significantly reduce the emission of SO2 and affect the production of NO_(x)in the furnace.With the increase of desulfuri⁃zer input,SO2 emission concentration decreases rapidly.As the frequency of limestone feeder increases from 5.6 Hz to 13.5 Hz,the SO2 con⁃centration at the inlet of absorption tower decreases from 360.4 mg/m^(3)to 6.9 mg/m^(3).At the same time,the desulfurizer input in the furnace can promote the chemical reaction of intermediate products such as HCN and NH3 to generate more NO_(x).The input amount of desulfurizer in furnace should be rationally selected.The results can provide reference for optimization of low load operation performance and the reduction of pollutant emissions in 350 MW CFB boiler.