600MW四角切圆锅炉流场非均匀性与SNCR尿素喷射优化研究

对四角切圆锅炉内流场非均匀性进行研究,为SNCR尿素喷射优化提供方案,以提高SNCR的NOx脱除效率。采用数值模拟的方法对不同负荷下的流场进行分析,并采用后处理的方法得到NOx浓度分布,将结果与电厂实际运行数据进行对比,验证数值模型的准确性。四角切圆锅炉内流场非均匀程度较高,采用常规的SNCR尿素喷射方法导致喷射点不在窗口温度范围内,效率较低。针对该问题提出两种解决途径,采用燃尽风消旋的方式,或采用基于尾部烟道NOx监测的动态调控。不同负荷下窗口温度所在位置不同,两种解决途径均需要考虑负荷的影响。采用燃尽风消旋的方式能够降低流场非均匀程度。采用基于尾部烟道NOx监测的动态调控的方式能够适应炉内非均匀流场特性进行动态喷射。

Research on Non-uniformity of Flow Field in 600MW Tangential Fired Boiler and Urea Jet Optimization in SNCR

The non-uniform flow field is discussed, for providing solutions about urea jet optimization in SNCR, in order to increase efficiency of SNCR. Flow fields of different load are analyzed by numerical simulation, and get the NOx density distribution by post-processing. The results contrast with actual operating data of power plant to verify the accuracy of the numerical mode. The non-uniform level of flow field is high in tangentially fired boiler, and the traditional method of urea jet has low efficiency for the urea may not in the reaction temperature. Two methods are proposed for the issue. Use OFA vortex elimination or dynamic control based on NOx monitor in boiler back end ductwork. The position of reaction temperature is different in different load, and the factor of load must be considered. The non-uniform level can be reduced by OFA vortex elimination. The non-uniform characteristics can be used by dynamic control based on NOx monitor in boiler back end ductwork for dynamic urea injection.