Abstract In this study, several methods are proposed to improve the denitrification (De-NOx) performance of the selective catalytic reduction (SCR) system. To illustrate how the proposed methods can be applied, the numerical analysis for the SCR system of an industrial-scale thermal power plant is conducted. There are two important indices affecting the performance of SCR system: one is the degree of mixing of the injected NH3 and the other is the uniformity of flow velocity before entering the catalyst layer. To improve the NH3 mixing, a static mixer in a location downstream of the ammonia injection grid (AIG) is generally installed. However, the uniformity of flow velocity distribution is severely aggravated as the mixer induces vortex. Therefore, it is suggested to place the mixer away from the catalyst layer to enhance the NH3 mixing and the uniformity of flow velocity together. The effect of the number of injection nozzles of the AIG on the SCR performance is also investigated. The number of nozzles of the ammonia injection grid can be reduced without affecting the uniformity in flow velocity. However, too much reducing the number of nozzles would result in improper ammonia mixing. Therefore, it is recommended to reduce the number of nozzles within a tolerable range of the NH3 mixing.

中文翻译：

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燃煤电厂工业规模选择性催化还原脱硝系统氨混合改进数值分析

摘要 在这项研究中，提出了几种方法来提高选择性催化还原 (SCR) 系统的反硝化 (De-NOx) 性能。为了说明如何应用所提出的方法，对工业规模热电厂的 SCR 系统进行了数值分析。影响SCR系统性能的重要指标有两个：一是注入NH3的混合程度，二是进入催化剂层前流速的均匀性。为了改善 NH3 混合，通常在氨喷射网格 (AIG) 下游位置安装静态混合器。然而，由于混合器引起涡流，流速分布的均匀性严重恶化。所以，建议将混合器放置在远离催化剂层的位置，以增强 NH3 混合和流速的均匀性。还研究了 AIG 喷嘴数量对 SCR 性能的影响。可以在不影响流速均匀性的情况下减少喷氨格栅的喷嘴数量。但是，过多地减少喷嘴数量会导致氨混合不当。因此，建议在NH3混合的容许范围内减少喷嘴数量。喷嘴数量减少过多会导致氨混合不当。因此，建议在NH3混合的容许范围内减少喷嘴数量。喷嘴数量减少过多会导致氨混合不当。因此，建议在NH3混合的容许范围内减少喷嘴数量。