Kinetic and experimental study of multimodal PM generation in coal char combustion

IF 5.8 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2025-06-04 DOI:10.1016/j.combustflame.2025.114272

Yimin Shang , Chen Wang , Haiyu Huang , Ying Yu , Xuan Yang , Guangyao Wang , Lei Chen , Yanqing Niu

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引用次数: 0

Abstract

A char burning and particulate matter kinetics (CBPMK) model has been further developed within a spherical coordinates system. It considers the mechanisms of volatilization, nucleation, condensation, coagulation-coalescence, char fragmentation, and mineral melt polymerization. In this model, char is simplified to a three-dimensional discrete spherical shell filled with carbon, ash, and macropore. To effectively simulate char fragmentation and mineral melt polymerization, an "effective connection" assumption is proposed, which facilitates the accurate modeling of fine/coarse particulate matter (PM) generation. The simulation results demonstrate a high degree of accuracy, with errors consistently below 10%. During char combustion, the mineral volatilization rate drops sharply due to the rapid decrease in particle temperature, resulting in the total mineral volatilization reaching the maximum within 0.01 -0.03 seconds. The number density of ultra-fine PM exhibits a bell-shaped curve, initially rising before dropping. Meanwhile, fine PM begins to generate in the early stage of combustion with a smooth process. In contrast, coarse PM generation is relatively delayed but then increases rapidly. Furthermore, an increase in ambient combustion temperature promotes the generation of ultra-fine PM and coarse PM. Based on the mass generation at 1100°C, ultra-fine PM increases by 8% (1300°C) and 107% (1500°C), while coarse PM increases by 32% (1300°C) and 51% (1500°C). The change of fine PM is related to ash melting, increasing when the ambient combustion temperature is below the ash flow temperature and decreasing when it's above, with the ratio of increase for fine PM is 45% (1300°C) and 26% (1500°C). Additionally, an increase in char particle size results in increasing generation of coarse PM while decreasing the generation of ultra-fine PM and fine PM. From 45-75 μm to 90-125 μm, ultra-fine PM and fine PM decreases by 66% and 17%, while coarse PM increases by 48%.

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煤焦燃烧中多模态PM生成的动力学与实验研究

在球坐标系下进一步建立了焦炭燃烧和颗粒物质动力学模型。它考虑了挥发，成核，缩聚，混凝-聚结，焦炭破碎和矿物熔体聚合的机制。在该模型中，炭被简化为由碳、灰分和大孔组成的三维离散球壳。为了有效地模拟煤焦破碎和矿物熔体聚合，提出了“有效连接”假设，有助于精确模拟细/粗颗粒物（PM）的生成。仿真结果表明，该方法具有较高的精度，误差始终在10%以下。在炭燃烧过程中，由于颗粒温度的快速降低，矿物挥发速率急剧下降，导致矿物总挥发在0.01 -0.03秒内达到最大值。超细PM的数量密度呈先上升后下降的钟形曲线。同时，细颗粒物在燃烧初期开始生成，过程较为平稳。相比之下，粗PM的产生相对延迟，但随后迅速增加。此外，环境燃烧温度的升高促进了超细PM和粗PM的产生。在1100℃的质量生成基础上，超细PM增加了8%（1300℃）和107%（1500℃），而粗PM增加了32%（1300℃）和51%（1500℃）。细粒PM的变化与灰熔化有关，当环境燃烧温度低于灰流温度时增加，高于灰流温度时减少，其中细粒PM的增加比为45%（1300℃）和26%（1500℃）。此外，炭粒度的增加导致粗粒PM的生成增加，而超细粒PM和细粒PM的生成减少。从45 ~ 75 μm到90 ~ 125 μm，超细PM和细PM分别减少66%和17%，粗PM增加48%；

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来源期刊

Combustion and Flame 工程技术-工程：化工

CiteScore

9.50

自引率

20.50%

发文量

631

审稿时长

3.8 months

期刊介绍： The mission of the journal is to publish high quality work from experimental, theoretical, and computational investigations on the fundamentals of combustion phenomena and closely allied matters. While submissions in all pertinent areas are welcomed, past and recent focus of the journal has been on: Development and validation of reaction kinetics, reduction of reaction mechanisms and modeling of combustion systems, including: Conventional, alternative and surrogate fuels; Pollutants; Particulate and aerosol formation and abatement; Heterogeneous processes. Experimental, theoretical, and computational studies of laminar and turbulent combustion phenomena, including: Premixed and non-premixed flames; Ignition and extinction phenomena; Flame propagation; Flame structure; Instabilities and swirl; Flame spread; Multi-phase reactants. Advances in diagnostic and computational methods in combustion, including: Measurement and simulation of scalar and vector properties; Novel techniques; State-of-the art applications. Fundamental investigations of combustion technologies and systems, including: Internal combustion engines; Gas turbines; Small- and large-scale stationary combustion and power generation; Catalytic combustion; Combustion synthesis; Combustion under extreme conditions; New concepts.