Abstract The ash-related problems of fouling and slagging occur easily during high-alkali coal combustion in boilers. In this study, numerical calculations were performed to investigate the sodium migration mechanism and ash deposition on heating surfaces in a large-scale circulating fluidized bed (CFB) boiler during the burning of high-alkali coal. The calculation principle was based on a comprehensive three-dimensional CFB combustion model and a sodium migration model from our previous study. The computing object of this study was a 300 MW subcritical CFB boiler. By performing a simulation, the distributions of NaCl(g) and Na2SO4(g) along the furnace were displayed. The rates of sodium deposition via condensation, inertial impaction, and thermophoresis on the water walls and suspended panels were analyzed. Additionally, the net deposition rates of fly ash on the water walls and suspended panels were determined. Then, the tendency of fouling and slagging in different areas of the CFB furnace could be predicted and judged. Calculation results for the gas–solid flow, furnace temperature, and gaseous species agreed with the measured data.

中文翻译：

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大型循环流化床锅炉高碱煤燃烧钠转化的CFD模拟

摘要 锅炉在高碱煤燃烧过程中容易出现结垢、结渣等与灰有关的问题。在这项研究中，通过数值计算研究了大型循环流化床 (CFB) 锅炉在燃烧高碱煤过程中钠迁移机制和受热面上的灰沉积。计算原理基于我们之前研究中的综合三维 CFB 燃烧模型和钠迁移模型。本研究的计算对象是一台 300 MW 的亚临界 CFB 锅炉。通过进行模拟，显示了 NaCl(g) 和 Na2SO4(g) 沿炉膛的分布。分析了通过冷凝、惯性撞击和热泳在水壁和悬浮板上的钠沉积率。此外，确定了飞灰在水墙和悬浮板上的净沉积率。然后，可以预测和判断CFB炉不同区域结垢和结渣的趋势。气固流量、炉温和气体种类的计算结果与实测数据一致。