颗粒-壁面相互作用对石墨粉尘在高温气冷堆蒸汽发生器换热管表面沉积过程的影响

摘要

The deposition of graphite dust on steam generator (SG)tubes is a highly concerned issue for operation and maintenance of high-temperature gas-cooled reactor (HTGR),as the distribution of radioactivity is directly affected.In this paper,the computational fluid dynamics (CFD)study on graphite dust deposition on SG tubes was presented,with emphasis of the particle-wall interaction.From a view of kinetic energy dissipation,a critical capture velocity model was adopted to account for particle-wall collisions and incorporated into CFD simulation.The results show that the hit-and-stick assumption significantly overestimates the deposition rate of graphite dusts. With reasonable consideration of particle rebound,the deposition rate first increases then decreases with particle diameter increasing,showing a maximum at 3 μm.The analysis of spatial distribution indicates that largest deposition rates appear on middle rows of tubes.%石墨粉尘在高温气冷堆蒸汽发生器换热管表面的沉积直接影响一回路放射性分布,因而备受学界和业界的关注。本文采用临界粘附速度模型研究石墨粉尘颗粒的碰壁过程,并将其耦合入蒸汽发生器一次侧的气固两相流模拟计算中,得到了石墨粉尘颗粒在换热管束间的输运和沉积规律。结果表明,考虑颗粒-壁面相互作用后,石墨颗粒沉积率显著减小,其与粒径的关系也有所不同。沉积率随粒径的增大先增大后减小,最大沉积率对应粒径约3μm。空间分布规律上,小颗粒迎风第1排管沉积率相对最大,2μm 以上颗粒最大沉积率发生在第4~6排管。