四级过热器管束壁面颗粒沉积的数值模拟
收稿日期: 2017-02-18
修回日期: 2017-04-11
网络出版日期: 2017-06-30
基金资助
国家自然科学基金项目（91544108，51376147）
Numerical Simulation of Ash Deposition on Wall of Fourth-Stage Superheater Pipes
Received date: 2017-02-18
Revised date: 2017-04-11
Online published: 2017-06-30
以某12 MW生物质锅炉炉膛出口四级过热器为研究对象，建立了考虑惯性、布朗力和热泳力作用下灰颗粒的沉积模型，同时耦合碱金属盐蒸气的凝结效应以及颗粒反弹、粘附机制。基于数学模型考察了管排截距与灰中KCl含量对过热器管束壁面颗粒沉积质量的影响。结果表明，灰颗粒中碱金属盐KCl含量由15%增至25%后，各排管壁灰颗粒沉积质量显著增加，首排单管迎风面沉积质量由4.82 × 10−7 kg/m2增大为4.03 × 10−6 kg/m2。当管束的纵向节距由1.5D增大至2.5D时，各排管壁迎风面与背风面颗粒沉积质量显著增加。首排管束下游壁面形成不规则初始沉积形貌，其主要源于含尘气流进入下游管排，烟气冲刷位置、涡生成与脱落位置发生变化所导致。
王毅斌 , 谭厚章 , 刘鹤欣 , 许伟刚 , 曹锐杰 . 四级过热器管束壁面颗粒沉积的数值模拟[J]. 新能源进展, 2017 , 5(3) : 163 -169 . DOI: 10.3969/j.issn.2095-560X.2017.03.001
For the fourth stage superheater at the outlet of a 12 MW biomass-fired power plant, an ash particle deposition model considering the condensation of gaseous alkali metal salts and rebound/stick of ash particles was developed by considering of the inertial force, Brownian force and thermophoretic force. The effects of tube arrangement and KCl content in ash particles on ash deposition characteristics were investigated based on a mathematical model. Results showed that the ash deposited mass on tube surface for each row was sharply increased with the KCl content increased; as the KCl content increased from 15% to 25%, and the deposited mass on the windward side of the first row increased from 4.82 × 10−7 kg/m2 to 4.03 × 10−6 kg/m2. The deposits on tube wall of each row were increased when the longitudinal pitch varied from 1.5D to 2.5D. The formation of irregular depositing characteristic around the tube was mainly attributed to the scouring position variation for upstream flue gas to downstream of the tube bundle, and the generation and shedding position of vortex.
Key words： superheater; ash particle; deposition; condensation; salt vapor
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