小型循环流化床锅炉的选择性非催化还原脱硝工艺改造

摘要

In order to deal with the increasing environmental problems and further reduce Nox emissions, a 15 t/h circulating fluid bed boiler was retrofitted by selective noncatalytic reduction ( SNCR) denitrification tech-nology.Firstly the flow field in the cyclone separator was simulated, and the results show that the velocity distribu-tion of flue gas exhibits a pretty symmetry, which can provide a good mixing and reaction condition for the SNCR denitrification process.Based on that, the SNCR denitrification system is designed and installed for the boiler in ac-cordance with its structural characteristics and practical operation.After debugging, the denitrification system runs stably and economically, and Nox concentrations at high temperature gas duct and tail duct decreased by 54.9% and 44.9% respectively.The concentration of Nox emission and the amount of escaped ammonia are far below the limits of relevant standards.%为应对日益严峻的环境问题,进一步降低NOx排放浓度,对一台15 t/h循环流化床锅炉进行选择性非催化还原(SNCR)脱硝工艺改造.首先对旋风分离器内的流场进行了模拟,模拟结果表明,烟气在旋风分离器内的速度分布呈现出较好的对称性,能够为SNCR脱硝过程提供良好的混合及反应条件.在此基础上,根据锅炉结构特征和实际运行情况,为锅炉设计并安装脱硝系统.经过调试,SNCR脱硝系统运行稳定,经济性良好.锅炉高温烟道和尾部烟道内烟气中的NOx浓度分别降低了54.9%和44.9%,NOx排放浓度和氨逃逸量均远低于相关标准的限值.