石灰石脱硫对循环流化床中NO_x生成和排放的影响  

Limestone Effects on NO_x Formation & Emission in CFB Combustors

作　　者：侯祥松[1] 李金平[1] 张海[1] 赵石铁[1] 吕俊复[1] 岳光溪[1] 

机构地区：[1]清华大学

出　　处：《电站系统工程》2005年第1期5-7,16,共4页Power System Engineering

摘　　要：石灰石脱硫是循环流化床燃烧技术的优势之一。但是运行实践表明,加入石灰石对循环流化床燃烧过程中 NOX的排放有一定的负面影响,烟气中的 NOX 浓度增大了 20%～30%。为了提高脱硫效率采用较高的钙硫比时,NOX 的排放浓度也会增大。综合分析了石灰石脱硫对循环流化床中 NOX 排放的影响机理,并从化学动力学的角度对该结果进行了理论分析。认为在氧化性燃烧气氛中,石灰石产生的氧化钙能促进挥发分中的 NH3氧化生成 NO,并促进 N2O 转变成在高温下更稳定的 NO,造成烟气中 NOX浓度增高。Circulating Fluidized Bed (CFB) combustion technology has advantages in economically controlling SO2 and NOx emissions for power generation. However, it is found that NOX emission increased up to 20%~30% when limestone is added into the combustor for desulphurization, especially with rather high Ca/S ratio. The phenomenon of NOx augment was discussed based on associated chemical kinetics. The catalytic oxidization effect, preferential conversion effect between HCN and NH3, and reducing effect were analyzed. It is found that CaO decomposed CaCO3 favors the conversion reactions of NH3 from coal volatile to NO, as well as unstable N2O to rather stable NO.

关 键 词：循环流化床燃烧技术 NOX排放 NOx浓度 钙硫比 石灰石 烟气 脱硫效率 排放浓度 NH3 氧化钙 

分 类 号：TM621[电气工程—电力系统及自动化] TK229[动力工程及工程热物理—动力机械及工程]