某700MW切圆燃烧机组低氮燃烧贴壁风系统数值计算与应用分析

Numerical Simulation and Application Analysis of Near-wall Air Distribution System for Low Nitrogen Combustion of a 700MW Tangential Combustion Unit

针对某2′700MW超临界四角切圆锅炉高温腐蚀问题,提出了加装贴壁风系统及低NOx燃烧优化改造方案,并通过对改造方案满负荷炉膛燃烧状态进行一系列数值计算,以及对主燃区近壁O2、CO、H2S等组分和烟气温度分布进行分析。结果显示,增加2层/8只反切布置贴壁风喷口后,上层燃烧器至还原区上部近壁O2浓度显著增加,CO、H2S浓度明显下降,烟气温度降低。贴壁风系统可以有效防治还原区侧墙水冷壁高温腐蚀。结合改后的现场调整试验,分析发现贴壁风可以改善炉膛出口烟气温度分布,降低左右两侧烟气温度偏差,对于四角切圆锅炉水平烟道对流过热面安全运行具有重要意义。增加贴壁风后,锅炉在保证经济性的条件下,可以提高锅炉运行的安全性和环保性。

In order to solve the high temperature corrosion problem of a 2×700 MW supercritical tangentially-fired boiler, a modification scheme of adding a closing-to-wall air system and optimizing the combustion of low NOx was proposed, and a series of numerical simulation were carried out for the combustion state of the full load furnace of the modification scheme, and the distribution of components such as O2, CO and H2S and the flue gas temperature near the wall of the main combustion zone were analyzed. The results show that after adding 2 layers/8 anti tangentair nozzles of the closing-to-wall air system,the concentration of O2 near the wall of the upper layer burner to the upper part of the reduction zone increases significantly, the concentration of CO and H2S decreases significantly, and the temperature of the flue gas decreases. The closing-to-wall air system can effectively prevent the high temperature corrosion of the water wall of the side wall in the reduction zone. Combined with the modified field adjustment test, it is found that the closing-to-wall air can improve the temperature distribution of flue gas at the outlet of the furnace and reduce the temperature deviation of the flue gas at the left and right sides, which is of great significance for the safe operation of the convective superheated surface of the horizontal flue gas in the tangentially-fired boiler. The safety and environmental protection of the boiler operation can be improved under the condition of economy when the closing-to-wall air system is added.