The adverse effect of ultrafine particulate matter (PM) from the combustion of solid fuels calls for fundamental insights to guide effective control strategies. In this work, we investigated the ultrafine PM formation from burning several solid fuel samples, with special emphasis on the relationship with an emerging field of flame synthesis. Diluted fly ash was sampled and characterized in a bench-scale flat-flame burner at the early stage (∼40 ms) and in a 25 kW quasi-one-dimensional combustor at the burnout stage (∼1.5 s). Then, the population balance model framework was transplanted from the community of flame aerosol synthesis to simulate the particle size distributions (PSDs). From the experiments, unimodal submicron PSDs were revealed for the combustion of coal, rice husk, and sewage sludge under 40 ms of residence time and a postflame ambience of 1500 K and 20 vol % O₂. The compositional analysis reveals both the contributions from Na/K/P/S and from refractory species are important for ultrafine PM formation. This vaporization-nucleation mechanism highlights the similarity between solid fuel combustion and flame synthesis. However, the difference is raised by the medium and coarse mode PM that only appears in solid fuel combustion. The volatilized mineral and the ultrafine PM can be scavenged via coagulation, and the scavenged ratio takes ∼10–60% of the total volatilized minerals for different coal samples. This ratio is inversely correlated with the volatilized minerals on a basis of ash input.

中文翻译：

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煤粉，生物质和废物燃烧中超细颗粒的形成：了解与火焰合成过程的关系

固体燃料燃烧产生的超细颗粒物（PM）的不利影响需要基本见解，以指导有效的控制策略。在这项工作中，我们研究了燃烧多个固体燃料样品而形成的超细颗粒物，并特别强调了与新兴的火焰合成领域之间的关系。稀释的粉煤灰在早期阶段（约40毫秒）被采样到台式台式火焰燃烧器中，在燃尽阶段（约1.5 s）在25 kW准一维燃烧室中进行表征。然后，从火焰气溶胶合成社区移植人口平衡模型框架，以模拟粒径分布（PSD）。通过实验，揭示了单峰亚微米PSDs用于燃烧煤，稻壳，₂。成分分析表明，Na / K / P / S和难熔物质的贡献对于超细颗粒物的形成都很重要。这种汽化成核机理突出了固体燃料燃烧与火焰合成之间的相似性。但是，仅在固体燃料燃烧中出现的中模和粗模PM会增加这种差异。挥发的矿物质和超细颗粒物可以通过凝结清除，清除率占不同煤样总挥发矿物的10-60％。根据灰分输入，该比率与挥发的矿物质成反比。