喷氨格栅处烟气速度场对高效SCR均流与还原剂混合性能的影响

Influence of the Flue Gas Velocity Field at an Ammonia-injection Grid on Uniform Flows and Reducing-agent Mixing Performance of a High-efficiency SCR(Selective Catalytic Reduction) Device

随着SCR脱硝效率的上升,喷氨格栅(AIG)处烟气速度场在SCR均流与混合技术中变得越来越重要。以某高效电站SCR为研究对象,利用经冷态模型校验过的SCR数值模型,分析AIG处烟气速度场10种典型变化对电站SCR系统内均流与还原剂混合性能的影响。结果显示,对高脱硝效率的SCR系统,AIG处烟气速度场变化对催化剂入口界面上氨氮比分布影响很大,对入口界面上速度场也有一定影响。设计中控制AIG处烟气流速不均匀性可以提高SCR内均流与混合的品质。在AIG处流速不均匀性控制得较好的高效SCR中,随着AIG处流速不均匀性上升,催化剂入口界面上氨氮比不均匀性增大;AIG处速度场与催化剂处速度场具有相似性。

With an ever increasing SCR (Selective Catalytic Reduction) system denitration efficiency,the flue gas velocity field at an ammonia-injection grid (AIG) becomes ever more important in SCR system uniform flow and mixing technology. With the SCR system in a high efficiency power plant serving as an object of study,analyzed was the influence of ten typical changes of the flue gas velocity field at the AIG on the uniform flow and reducing agent mixing performance in the SCR system of the power plant by using a SCR system numerical model which has been verified by a cold state model. It has been found that for the SCR system with a high denitration efficiency,any changes to the velocity field at the AIG exercise a great influence on the distribution of ammonia-nitrogen ratio at the interface of a catalyzer inlet and also a definite influ-ence on the velocity field at the inlet interface. In a design process,the control of the inhomogeneity of the flow speed at the AIG can enhance the quality of the uniform flow and mixing in the SCR system. In a high-efficiency SCR system in which a relatively good control over the inhomogeneity of the flow speed at the AIG has been achieved,with an increase of the inhomogeneity,the nonuniformity of the ammonia-nitrogen ratio at the catalyzer inlet will increase. The velocity field at the AIG and that of the catalyzer have a similarity.