600 MW机组中速磨煤机的综合改进

Comprehensive Retrofit on the Medium-speed Pulverizer of a 600 MW Unit

某600 MW机组SCR脱硝系统入口烟气中NOx质量浓度(NOx初始排放质量浓度)难以达到性能保证值,结合现场试验,对中速磨煤机内部结构进行改进,并对风煤比曲线进行优化。结果表明:制粉系统的一次风量偏大是造成NOx初始排放质量浓度偏高的主要原因;对中速磨煤机进行综合改进后,可以在保持合理风速的前提下至少减小10%一次风质量流量,在不降低锅炉运行经济性的前提下,NOx初始排放质量浓度下降了20 mg/m^3以上。

To solve the problem that the inlet NOx mass concentration of the SCR denitration system(initial NOx emission concentration)is difficult to satisfy the requirement to guarantee the performance of a 600 MW unit,a retrofit was conducted on the interior structure of the medium-speed pulverizer based on field tests,while the curve of wind-coal ratio was optimized.Results show that the high initial NOx emission concentration is mainly caused by the large primary air flow in the pulverizing system.Through comprehensive retrofit on the medium-speed pulverizer,the primary air mass flow could be reduced by 10%within a reasonable range of wind speed,thus to reduce the initial NOx emission concentration by 20 mg/m^3 without reducing the boiler operation economy.