【作者】 王伟；

【导师】 周慎杰；

【作者基本信息】 山东大学 ， 化工过程机械， 2010， 硕士

【摘要】 随着我国对氮氧化物(NOx)排放标准的提高,以燃煤为主的火电厂如何减少氮氧化物的排放越来越受到重视。在众多的脱硝方法中,选择性催化还原(SCR)烟气脱硝技术具有脱硝效率高、运行可靠、无副产物、装置结构简单等优点,在世界上得到了广泛的应用。近年来,对SCR脱硝技术的研究主要集中在脱硝反应器流场优化和催化剂的研发上,如何提高脱硝效率,延长催化剂的寿命等相关问题是研究的热点。随着计算流体力学和计算机技术的发展,利用高效、便捷的计算流体力学软件对SCR脱硝系统进行数值模拟仿真,可以为脱硝反应器烟道、导流板及喷射系统的设计和改进提供重要参数。本文以某电厂600 MW机组所配置的SCR烟气脱硝装置为研究对象,利用FLUENT流体力学数值计算软件,对SCR反应器入口烟道流场进行了数值仿真计算。主要研究内容如下：通过对SCR反应器入口烟道流场的数值模拟,分析了不同数量的导流板时入口烟道流场分布,结果表明随着导流板数量的增加,入口烟道流场变得更均匀,但导流板数量的增加给SCR反应器带来更大的压降；当导流板的分布到一定程度后,导流板数量的增加对入口烟道流场的改善变得非常微弱。通过分析喷射格栅对入口烟道流场的影响,结果表明构成喷射格栅的管路对烟道流场有改善作用,且双层管路排布的喷射格栅比单层管路的作用更好。通过对入口烟道内烟气与还原剂混合的数值模拟,结果表明通过对喷嘴分区并设定不同的喷射速度,可以很好的改善烟气与还原剂的混合,且单层管路的喷射格栅比双层管路更有利于烟气与还原剂的分布。更多还原

【Abstract】 With nitrogen oxides(NOx) emission standards to be more stringent, it attracts more and more attention to reduce nitrogen oxides from coal-fired power plants. The selective catalytic reduction(SCR) technology for flue gas has been used widely in power plants all over the world, which has the advantage of the high denitration efficiency, reliability service, no by-products, simple device, and so on. In recent years, the research on SCR DeNOx technology mainly focuses on the optimization of flow field of SCR and the preparation of catalyst. Research focus is how to improve denitration efficiency, extend the life of the catalyst, and so on. With the development of computational fluid dynamics and computer technology, we can simulate SCR DeNOx system using of efficient, convenient computational fluid dynamics software. The results can provide important parameters for the design and improvement of flue, guide vanes and the injection system.Using computational fluid dynamics software FLUENT, the flow field of the entrance flue of SCR in a 600MW power plant unit is simulated in this paper. The main research contents and results are as follows. The flow field of the entrance flue of SCR is simulated when the number of guide vanes is different. The results show that with the increase of the number of guide vanes, the flow field of flue becomes more uniform and the pressure drop is greater. Meantime, the effect of guide vanes becomes weak when the distribution of guide vanes gets to a certain extent. The role of injection grid to the flow field of flue is analyzed, the results show that injection grid pipings can improve the flow field of flue and the role of double-pipe arrangement is better than single pipeline. The mixing of flue gas and reducing agent in entrance flue of SCR is numerical simulated. The results show that it can improve the mixing and the concentration distribution of flue gas and reducing agent in the flue by dividing the nozzles as different areas and setting different injection speeds. Moreover, single-pipeline in the injection grid is more beneficial to the distribution of flue gas and reducing agent than double-pipelines.更多还原