SCR催化剂磨损原理探究及优化方案分析

Exploration on causes of SCR catalyst wear and the optimization scheme

选择性催化还原(SCR)是目前应用最广泛、最成熟的燃烧后脱硝技术,但在工程实践过程中存在诸多问题,其中由于惯性作用导致烟气内飞灰颗粒集中在尾部烟道近锅炉侧,造成了飞灰颗粒对SCR脱硝催化剂局部磨损、积灰严重,脱硝装置效率大幅下降。针对此类问题,通过分析催化剂磨损原因和机理,设计了改造方案:在烟道内加装百叶窗导流板优化流场,加装氨-烟混态扰流发生器,通过计算流体动力学(CFD)软件进行可行性验证。结合工程实践,发现优化改造后能够改善尾部烟道内飞灰颗粒的质量浓度分布,使得尾部烟道内流场分布更均匀,有效解决催化剂局部磨损的问题。

Selective Catalytic Reduction(SCR)is the most widely used and mature post-combustion denitration technology by far,but there are many problems in engineering practices.The ash particles in flue gas concentrating in tail flues near boiler side because of inertia can result in local wear and ash accumulation of SCR denitration catalyst,which dramatically reduces the efficiency of denitration units.A targeted optimization scheme was designed through analyzing the cause and mechanism of catalyst wear,in which the flow field in the flue was optimized by installing louver guide plates and ammoniasmoke mixed vortex generators.The feasibility of the scheme was verified by CFD.Combined with the engineering practice,the modification installing louver guide plates and an ammonia-smoke mixed vortex generator in the tail flue can improve the uniform distribution of particle mass concentration in the flue and solve the local wear of catalyst effectively.