燃煤烟气低温SCR脱硝中试研究

Pilot-scale study of selective catalytic reduction of NO_x at low temperature

低温选择性催化还原（SCR）脱硝是国内外脱硝技术研发的热点,但目前主要集中在实验室小试范围,无法完全反映催化剂在实际烟气中的运行状况。在30 t/h循环流化床燃煤锅炉脱硫除尘装置后建设了2 000~5 000 m3/h的SCR脱硝中试装置,经系统研究发现,中试使用的蜂窝式催化剂对SO2和NO具有很强的吸附能力,且反应温度、喷氨速率和气体空速均会影响催化脱硝效率。为期5 d的连续运行实验结果表明,催化剂的脱硝效率一直稳定在30%~50%,并未发现明显的失活,这证明设计除雾除尘器、较大的混合器、混合器与反应器间较长的管路均有利于缓解催化剂因SO2、H2O和飞灰中的碱性金属导致的失活。

Selective catalytic reduction（ SCR） of NO x at low temperature is among the leading edge of the emerging hotspot of deNO x technologies. However,most of the reported investigations were bench-scale study,which were limited to represent the performance of catalysts at real applications. With the successful construction of pilot scale（ 2 000 ~ 5 000 m3/ h） SCR system at a coal-fired plant,we systematically investigated the low temperature SCR performance and adsorption property of the honeycomb catalysts. On one hand,it was observed that the honeycomb catalysts had good adsorption capacity both for NO x and SO2. On the other hand,reaction temperature,spraying rate of ammonia and space velocity all affected the removal efficiency of NO x. Furthermore,deactivation of the catalysts was not observed even after continuous running for 5 days. This indicates that the filter,the mixer,and the long duct from mixer to reactor contributed together to the relief of catalyst deactivation caused by the gaseous SO2 and H2O and by the alkaline poisonings in the fly ash.