Thermo and Fluid Dynamics (FLOW), Vrije Universiteit Brussel (VUB), Brussels, 1050, Belgium; Brussels Institute for Thermal-fluid Systems and clean Energy (BRITE), Vrije Universiteit Brussel (VUB) and Université Libre de Bruxelles (ULB), Belgium.
Accidental Risk Department, Institut Scientifique de Service Public (ISSeP), Liège, 4000, Belgium.
Environ Res. 2023 Nov 1;236(Pt 1):116714. doi: 10.1016/j.envres.2023.116714. Epub 2023 Jul 22.
Accurately measuring particulate matter emissions from biomass combustion is crucial for evaluating the performance of fuels, combustion appliances and flue gas cleaning methods. These measurements are essential for refining emission inventories for health risk assessments and environmental models and for defining pollution control strategies. However, as air quality standards become increasingly stringent and emission levels decrease, it is important to develop reliable, accurate measurement methods. This study presents a comprehensive evaluation of two particulate dilution systems, namely a full flow dilution (FFD) tunnel and a two-stage partial flow dilution system (porous tube diluter combined with ejector diluter, PTD + ED), for characterising the particle number size distribution from a wood pellet boiler. The maximum relative sampling errors due to not sampling isokinetically increase with particle size and dilution ratio (DR), but are less than 1% for particles smaller than 1 μm for both systems. The total particle number concentration with FFD is on average 35% lower than with PTD + ED, which suggests substantial particle loss during FFD. In addition with FFD, a strong negative correlation is observed between DR and the average particle size. On the other hand with PTD + ED, both the dilution air temperature and DR have no substantial influence on the particle number emissions. However, it is observed with both systems that the particle distribution is affected by coagulation, and this effect becomes more pronounced as dilution decreases. Overall, this work provides insights into the strengths and limitations of particulate dilution systems for accurately measuring emissions from biomass combustion, which can support the development of more reliable measurement methods and assist in implementing effective pollution control strategies.
准确测量生物质燃烧产生的颗粒物排放对于评估燃料、燃烧设备和烟气净化方法的性能至关重要。这些测量对于完善健康风险评估和环境模型的排放清单以及制定污染控制策略至关重要。然而，随着空气质量标准变得越来越严格，排放水平不断降低，开发可靠、准确的测量方法变得尤为重要。本研究全面评估了两种颗粒物稀释系统，即全流量稀释（FFD）隧道和两级部分流量稀释系统（多孔管稀释器与喷射器稀释器组合，PTD + ED），用于表征木屑颗粒锅炉的颗粒物粒径分布。由于未等速采样而导致的最大相对采样误差随粒径和稀释比（DR）的增加而增加，但对于两个系统，粒径小于 1μm 的颗粒物的误差均小于 1%。FFD 的总颗粒物数浓度平均比 PTD + ED 低 35%，这表明 FFD 过程中存在大量颗粒物损失。此外，与 FFD 相比，DR 与平均粒径之间存在强烈的负相关关系。另一方面，对于 PTD + ED，稀释空气温度和 DR 均对颗粒物排放没有实质性影响。然而，对于两个系统，均观察到颗粒物分布受到凝聚的影响，并且随着稀释比的降低，这种影响变得更加明显。总的来说，这项工作深入了解了颗粒物稀释系统在准确测量生物质燃烧排放方面的优缺点，这可以为开发更可靠的测量方法提供支持，并有助于实施有效的污染控制策略。
