X型静态混合器流场数值模拟研究

Study on numerical simulation of flow field for X-shaped static mixing device

为增强还原剂氨与烟气的混合均匀程度,研发了X型静态混合器,并将其应用于某电厂330 MW机组SCR脱硝反应系统。通过流体软件Fluent 6.3,采用标准κ-ε湍流模型进行数值模拟计算,研究了X型静态混合器压力降与覆盖率、烟气流速的特性曲线,氨氮摩尔比浓度与喷嘴数量的变化关系等,计算结果表明,在X型静态混合器作用下,90个喷嘴时首层催化剂入口NH3浓度Cv=2.7%,小于无混合器时288个喷嘴情况下NH3浓度Cv=3.1%,因此X型静态混合器能够有效提高氨气与烟气的混合均匀程度,减少喷嘴数量,简化喷氨格栅及其控制系统,满足SCR脱硝工程对静态混合器的设计要求。

In order to enhance the uniformity of mixing the reducing agent ammonia and flue gas,a new X-shaped static mixing device was developed and applied to the SCR denitrification system for a power plant 330 MW units. Numerical simulation of flow field for static mixing device was executed with standard κ-ε model based on FLUENT 6. 3 software.The characteristics of pressure drop for the X-shapedstatic mixing device with the coverage ratio and flue gas velocity was studied and the relationship between ammonia / nitrogen oxides molar ratio in concentration with number of nozzles was researched simultaneously. The simulation results showed that the concentration Cv = 2. 7% for ammonia / nitrogen oxides molar ratio in the role of X-shaped static mixer and the number of 90 nozzles,less than concentration Cv = 3. 1%with number of 288 nozzles and no static mixer,so the static mixing device could effectively improve the uniformity between ammonia and flue gas,reducing the number of nozzles,simplifying the ammonia injection grid（ AIG） and its control system met the design requirements of mixing device for SCR denification system.