邓磊,袁茂博,杨家辉,等. 宽负荷下切圆燃煤锅炉H2S分布特性的数值模拟研究[J]. 煤炭学报,2023,48(12):1−10. doi: 10.13225/j.cnki.jccs.2023.0248
引用本文: 邓磊,袁茂博,杨家辉,等. 宽负荷下切圆燃煤锅炉H2S分布特性的数值模拟研究[J]. 煤炭学报,2023,48(12):1−10. doi: 10.13225/j.cnki.jccs.2023.0248
DENG Lei,YUAN Maobo,YANG Jiahui,et al. Numerical simulation on H2S distribution characteristics of tangentially coal-fired boiler under wide loads[J]. Journal of China Coal Society,2023,48(12):1−10. doi: 10.13225/j.cnki.jccs.2023.0248
Citation: DENG Lei,YUAN Maobo,YANG Jiahui,et al. Numerical simulation on H2S distribution characteristics of tangentially coal-fired boiler under wide loads[J]. Journal of China Coal Society,2023,48(12):1−10. doi: 10.13225/j.cnki.jccs.2023.0248

宽负荷下切圆燃煤锅炉H2S分布特性的数值模拟研究

Numerical simulation on H2S distribution characteristics of tangentially coal-fired boiler under wide loads

  • 摘要: 锅炉采用空气分级燃烧降低NOx排放的同时也提高了主燃区H2S体积分数。炉墙壁面过高的H2S体积分数是加剧水冷壁高温腐蚀的重要因素。为保障新能源并网发电,大型燃煤机组灵活调峰的需求增加,不同负荷下的水冷壁近壁面H2S分布特性值得关注。笔者通过正交试验分析了切圆燃煤锅炉运行参数对水冷壁近壁面H2S体积分数分布的影响。选取一台超临界600 MW切圆燃煤锅炉建立数值模型,设计L16(45)正交工况,覆盖100% BMCR、75% THA,50% THA以及35% BMCR 4种负荷。建立了自定义SOx生成模型以确定燃料硫的析出和转化路径,模型包含多表面反应子模型以描述焦炭与O2/CO2/H2O等3种气体的异相反应,并确定焦炭气化反应消耗量占总消耗量的比例,进而对炉膛H2S空间分布进行了模拟计算。研究表明,近壁面高体积分数H2S区域主要位于投运燃烧器层中最下层燃烧器以下以及最上层燃烧器以上至SOFA层之间,烟气切圆沿炉膛高度增加逐渐增大是造成后一区域H2S体积分数较高的重要原因。35% BMCR负荷下水冷壁重点区域的H2S平均体积分数为364 μL/L,明显低于其他负荷。锅炉运行参数对重点区域H2S体积分数影响程度的排序为:锅炉负荷 > 一次风率 > 主燃区空气过量系数 > 假想切圆直径 > 燃烧器竖直摆角。研究锅炉运行参数对炉膛内H2S体积分数的影响幅度与效应,可指导不同负荷下运行参数的调节方向,为减轻锅炉调峰运行下水冷壁的高温腐蚀提供参考。

     

    Abstract: Air staged combustion reduces NOx emissions, but increases the H2S concentration in primary combustion zone. The excessive H2S concentration near the furnace wall is an important factor that aggravates the high-temperature corrosion of the water-cooled wall. With large-scale renewable power integrated into the grid, the demand for flexible peak-shaving operation of traditional thermal power units has increased. The H2S concentration distribution near the furnace wall under different boiler loads deserves attention. Hence, the influence of different operating parameters of tangentially coal-fired boiler on H2S concentration distribution near the furnace wall was investigated by orthogonal test. A supercritical 600 MW tangentially coal-fired boiler was selected to establish a numerical model. The L16(45) orthogonal numerical conditions was designed to cover four boiler loads, including 100% BMCR, 75% THA, 50% THA and 35% BMCR. A user-defined SOx generation model was employed to calculate the H2S concentration distribution inside the furnace. The release of fuel sulfur and mutual transformation of sulfur components were considered. At the same time, the model included a multiple surface reaction model for describing the heterogeneous reaction between coke and O2/CO2/H2O, and the ratio of the gasification rate to the consumption rate for char particle was calculated. The results show that the high H2S concentration areas are mainly located below the bottom burner that on operation and between the top burner and SOFA nozzle. The main reason for the high H2S concentration in the latter area is that the tangential circle of flue gas increases gradually along the furnace height. The orthogonal analysis indicates that the average H2S concentration in the key area of the furnace wall under 35% BMCR load is 364 μL/L, which is significantly lower than that under the other loads. In addition, the impact of operating parameters on the H2S concentration in key areas follows the order of boiler load > primary air rate > excess air coefficient of main combustion zone > imaginary tangent circle diameter > vertical swing angle of burner. Studying the amplitude and effect of boiler operating parameters on the H2S concentration in furnace can guide the adjustment direction of operating parameters under different loads, and provide reference for reducing the high-temperature corrosion of the water-cooled wall during boiler peak-shaving operation.

     

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