Electric Power Technology and Environmental Protection

【目的】为探究燃煤中砷元素在钒钛系脱硝催化剂上的赋存规律及中毒机制，提出应对砷中毒的有效措施。【方法】本文选 取燃用高砷煤的600 MW机组脱硝系统，对比进口与国产催化剂的运行数据；通过X射线荧光光谱分析砷积累规律；采用Ca（NO₃）₂ 和H₂O₂溶液对中毒催化剂进行再生实验，评估活性恢复效果；从煤质掺烧、催化剂配方优化及运行策略三方面提出改进方案。 【结果】研究表明，砷在催化剂入口端富集最显著，积累规律为：第一层>第二层>底部，运行8 000 h内砷饱和速率最快，砷元素 在催化剂上的累积接近饱和，之后累积速度逐渐趋缓；在失活最严重的8 000 h内，进口催化剂砷元素的累积速度超过国产催 化剂。而H₂O₂再生效果优于Ca（NO₃）₂，但因其强极性导致活性组分V₂O₅流失26%；掺烧高有机质或高CaO煤种可抑制 50% As₂O₃挥发；催化剂配方增大孔径分布并提高（V+W）/As摩尔比，可增强砷耐受性；分层添加催化剂比传统设计减少5%采 购成本。【结论】砷中毒可通过煤质掺烧抑制污染源、优化催化剂微孔结构与活性组分、实施“短周期逐层更新”运行策略综合应对，为高砷煤电厂脱硝系统提供经济高效的解决方案。

 [Objective]To investigate the accumulation pattern and poisoning mechanism of arsenic on vanadium titanium denitrification catalysts, and to propose effective measures to deal with arsenic poisoning. [Methods] A 600 MW unit denitrification system combusting high-arsenic coal was selected to compare the operation data of imported and domestic catalysts. The arsenic accumulation pattern was analysed by X-ray fluorescence spectrometry. Regeneration experiments of the poisoned catalysts were carried out by using Ca(NO3 )2 and H2 O2 solutions to assess the effect of activity restoration. The improvement scheme was proposed from the aspects of coal blending, catalyst formulation optimization, and operation strategy. [Results] The study showed that arsenic was most significantly enriched at the inlet end of the catalyst, and the accumulation pattern was as follows: the first layer > the second layer > the bottom. The arsenic saturation rate was the fastest within 8 000 h of operation, and the arsenic accumulated on the catalyst was close to saturation, and then the accumulation rate gradually slowed down. The accumulation rate of arsenic of imported catalysts was higher than that of domestic ones within the 8 000 h of the most serious deactivation. The regeneration effect of H2 O2 was better than that of Ca(NO3 )2 , but the strong polar solvent led to the loss of 26% of the active component V2 O5 . The blending of high-organic-mass or high-CaO coal could inhibit the volatilisation of As2 O3 by 50%. Catalyst formulations that increase the distribution of the pore sizes and increase the molar ratio of (V+W)/As could enhance the arsenic tolerance Layered addition of catalysts reduces the purchase cost by 5% compared to conventional designs. [Conclusion]Arsenic poisoning can be dealt with through coal blending to inhibit the pollution source, optimising the catalyst microporous structure and active components, and implementing the ‘short-cycle, layer-by-layer updating’ operation strategy, which provides a cost-effective and efficient solution for the denitrification system of high arsenic coal power plants.