基于SCR脱硝催化剂质量评判下的排序优化及效益分析

Sequencing optimization and benefit analysis based on quality evaluation of SCR denitration catalyst

以某一燃煤电厂3层催化剂M_(2)-N_(1)-N_(2)为实例,通过测试主要化学成分、比表面积、微量元素及脱硝率等指标,分析评判现有3层催化剂质量优劣,并优化3层催化剂的排序,确保NO_(x)达标排放。结果表明:与SCR催化剂N_(1)、N_(2)相比,SCR催化剂M_(2)中CaO、Al_2O_(3)等主要化学成分浓度小,参与烟气中SO_(3)气体反应生成CaSO_(4)和Al_2(SO_(4))_3的量较少,且不易在孔道中沉积,同时,烟气和飞灰中Na、Mg、Fe、K等微量元素在催化剂M_(2)表面产生的积聚量少,占据有效酸性位点数量少。通过测试整体脱硝率及单层脱硝率、优化原排序三层催化剂的顺序,确保了新排序下整体脱硝率满足NO_(x)排放要求,并从环境-经济-资源多维度进行效益分析,不同置换方法下的经济成本核算表明,新排序下SCR催化剂为该厂节省471.9万或330万元,节约了新鲜催化剂的制造资源,规避了催化剂在制造或处置过程中造成的环境污染环节,延长了催化剂使用寿命。

Taking the three-layer catalyst M_(2)-N_(1)-N_(2) of a coal-fired power plant as an example,the indexes of main chemical composition,specific surface area,trace elements and denitration efficiency were tested,the quality of the existing three-layer catalyst was analyzed and evaluated,and the sequencing of the three-layer catalyst was optimized,to ensure NO_(x) to meet the emission standard.The results showed that,compared with SCR catalyst N_(1)/N_(2),SCR catalyst M_(2) had less chemical composition of CaO and Al_(2)O_(3),which reacted with SO_(3)gas in the flue gas to generate less amount of CaSO_(4) and Al_(2)(SO_(4))_(3),and it was not easy to deposit in the channel.At the same time,trace elements,such as Na,Mg,Fe and K,in the flue gas and fly ash accumulated less on the surface of catalyst M_(2) and occupied less effective acid sites.The overall denitration efficiency was tested,and the denitration efficiency of the single-layer SCR catalyst was also explored.The original sequencing three-layer catalyst was optimized to ensure the overall denitration efficiency to meet NO_(x) emission requirements under the new sequencing.The benefit analysis was carried out from the multi-dimensions of environment,economy and resources.The economic cost accounting under different replacement methods showed that SCR catalyst under the new sequencing could save 4.719 million yuan or 3.3 million yuan for the plant.Moreover,it could save the manufacturing resources of the fresh SCR catalyst,and avoid the links of environmental pollution caused by the manufacture and handling of the SCR catalyst.SCR catalyst recycled would also prolong the life span of the catalyst.