300MWe循环流化床锅炉SNCR系统优化设计

The Optimal Design on the SNCR System in a 300 MWe CFB Boiler

随着中国最新环保标准的颁布,一部分循环流化床锅炉必须增设烟气脱硝设备以实现氮氧化物(NOx)的达标排放。针对300 MWe等级的大容量循环流化床(CFB)锅炉,从安全保障、技术实现、经济成本等角度详细比较了现有主流脱硝技术——选择性催化还原(SCR)和选择性非催化还原(SNCR)的可用性,并最终选取以尿素溶液作为还原剂的SNCR系统作为推荐方案。通过计算流体动力学(CFD)模拟方法,探究了不同尿素喷嘴布置方式、锅炉负荷等对尿素分布流场、脱硝效率及逃逸率的影响,并建议每部分离器设置10个喷嘴,且竖向均匀布置于分离器进口段内外侧,并给出了该SNCR系统的工艺优化改进建议。

In order to meet the updated emission regulation in China, some CFB boilers have to install the deNOx de- vices. For the 300MWe CFB boiler,the existing SCR and SNCR technologies are compared and the SNCR technology using urea as reductant is recommended in the view of technical, economic and safety concerns. By employing the CFD method, the different urea distributions inside the cyclone with different layout with different nozzle numbers for each cyclone are calculated and compared. The layout of 10 nozzles both inner and outer walls of cyclone inlet has the optimal performance. At the same time, the modification suggestions on process of urea transport, mixing and injection are provided.