大型煤粉锅炉SNCR过程数值研究分析论文.docVIP

大型煤粉锅炉SNCR过程数值研究 摘要：本文基于FLUENT软件平台，对410t/h燃煤锅炉中SNCR过程进行了建模和模拟计算，计算结果与实验测量数据吻合得很好，阐明了利用这种方法预测大空间，复杂温度场，复杂流场的锅炉炉膛中氮氧化物生成及还原过程的可行性。计算结果表明，在还原剂与氮氧化物初期混合条件有限的情况下，脱硝效果决定于物质的湍流扩散和温度场之间的相互作用。同时，还研究了在不同喷射截面上温度水平和氨氮摩尔比对SNCR过程的影响，表明喷射截面应取在平均温度位于SNCR“温度窗口”中部的截面所对应的高度处，该工况下脱硝率在42%以上，且随氨氮比由1.0提高到2.2，脱硝率增长约58%。但在综合考虑尾部漏氨时，应将氨氮摩尔比控制在1.4以下。 关键词：SNCR；大型煤粉锅炉；数值计算；脱硝率 文章编号： 中图分类号：TK229 文献标识码：A 学科分类号：470-2040 Numerical study of SNCR process in coal-fired boiler with large capacity Abstract: In this article, modeling and numerical simulation for the SNCR process in a 410t/h coal-fired boiler was conducted based on the platform supplied by FLUENT software. Consequently, the calculation result has good agreement with the data measured in field experiment, so the feasibility of predicting NOx formation and reduction processes in the furnace with large capacity, complex temperature field and complex flow field through the presented method is confirmed. The simulation result also shows that the NOx removal effect largely depends on the interaction between turbulence diffusion of the materials and temperature field, in the case that the reagent’s original mixing with NOx is quite limited. On the other hand, the influence of temperature level and molar ratio of NH3/NO in different injecting cross-sections on the SNCR process was studied as well. It is indicated that the injecting cross-section should be placed at the corresponding height of the cross-section, of which the temperature located in the middle of the SNCR “Temperature Window”. In that state, the NOx removal efficiency is above 42%. Meanwhile, it increases approximately by 58% when molar ratio of NH3/NO rises from 1.0 to 2.2. However, considering the NH3 leakage in the empennage area simultaneously, molar ratio of NH3/NO should be controlled bellow 1.4. Key words: SNCR; Coal-fired boiler with large capacity; numerical simulation; NOx removal efficiency 1 引言 随着环保要求的提高，大型电站锅炉的NOx排放标准也日益严格。在众多的NOx控制方法中，选择性非催化还原（Se