Developing And Optimization On Body Shape And Internal Configuration Of Selective Catalytic Reduction (SCR) Reactor

Selective Catalytic Reduction(SCR)is currently a most popular,reliable and high-efficient De-NOx technology worldwide with the characteristic of(i)high NOx removal efficiency over 90%,low NOx emission concentrate below 50mg/Nm3,(ii)small secondary pollution,which is very limited during the whole process due to SCR principle of NOx reduction with NH3 into N2 and H2 O,(iii)extensive application.SCR De-NOx technology has been employed extensively in many developed countries.However,due to its complicated system,the NOx removal efficiency of SCR is affected by flow field distribution,ammonia concentration distribution,reaction temperature,reaction time,catalyst performance,etc.The overall performance of SCR system is impacted relatively greatly by the reactor body shape and internal configuration based onthe study on related literatures and site survey.The developing and optimization on SCR reactor play a critical role to the performance of a SCR project.The Computational Fluid Dynamics(CFD)simulation on flow field or the physical model test is an important approach to develop and optimize SCR reactor,and accordingly proper reactor shape and internal configuration can be achieved to meet engineering index.In China,the study on SCR De-NOx process primarily focuses on partial optimization on De-NOx system,aiming at flue gas duct,corner,ammonia injection grid(AIG),ammonia mixer,guide vane and rectifier grid.Moreover,this study mostly covers SCR De-NOx projects in power industry.SCR retrofit for power industry has been basically completed,and the greatest challenge on NOx governance is onmiddle and small-size SCRDe-NOx projects in other industries especially for industrial boilers.With the characteristics of small capacity and huge quantity,these SCR De-NOx projects are challenging the developing and optimization on SCR system tremendously.In this dissertation,SCR reactor body shape and its internal configuration of key equipment was studied in depth by using the advanced CFD software STAR-CCM+ combined with physical model test.The study aims extensively at flow filed distribution,ammonia gas concentration distribution,ammonia gas concentration distribution,temperature distribution,maximum flue gas incident angle and unit pressure drop of various reactors,and covers developing and optimization on SCR reactor under different scenarios.Below are the main study points:(1)High-efficient SCR reactorThis type of reactor is universal and applicable to most working scenarios with dust or low dust.This high-efficient SCR reactor was developed and optimized to meet the index of flow filed distribution without adding guide vane.Furthermore,this SCR reactor can achieve a better maximum flue gas incident angle.(2)High-efficient SCR reactor with inlet diffuserAn inlet diffuser of SCR reactor was developed and optimized.The index of flow filed distribution can be met with this special reactor configuration combined with this trumpet-shaped inlet guide vane.(3)Low-dust SCR reactorA SCR reactor,applicable for low-dust work scenario,was developed and optimized.The index of flow filed distribution can be met by adding perforated plates with specified opening ratio at the reactor inlet.The three types of reactors presented above basically cover all SCR ones and are applicable to the developing and optimization on SCR reactor under various scenarios,furthermore,all three types of reactors have been successfully applied in SCR de-NOx projects.Finally,a SCR reactor with special configuration was studied and the developing philosophy on SCR reactor was extended by optimizing flue gas intake grid.