Effect of high geothermal environments on microscopic properties and oxidation processes of waterlogged coal

IF 6.4 2区工程技术 Q1 THERMODYNAMICS Case Studies in Thermal Engineering Pub Date : 2024-11-13 DOI:10.1016/j.csite.2024.105496

Xun Zhang, Chuang Li, Bing Lu, Fengwei Dai, Ge Huang, Ronghai Sun

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Abstract

In mines with deep levels and those exhibiting anomalous geothermal temperatures, high geothermal environments can affect the erosion process of waterlogged coal by immersion. To study the influence of a high geothermal environment regarding the self-ignition of waterlogged coal, immersion of the coals in aqueous solutions under various temperature conditions (room temperature 20 °C, 40 °C, 60 °C and 80°) for 30 days. Low-temperature nitrogen adsorption, infrared spectroscopy, and simultaneous thermal analysis were utilized to examine the alterations in the micro physicochemical structure and oxidation process of waterlogged coal samples at room temperature and high geothermal temperature. Compared with room temperature conditions, the high geothermal environment increased the number and volume of pores in the waterlogged coal, broke intermolecular hydrogen bonds, and increased the total number of reactive groups. These microstructural changes affected the oxidation process of the waterlogged coal, causing in the oxidation characteristic temperature points on the TG and DSC curves as well as the activation energies E of the second and third stages of TG being significantly lower than those of the waterlogged coal under room temperature conditions. This study suggests that the high geothermal environment enhances the spontaneous combustion tendency of waterlogged coal and accelerates its oxidation process.

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高地热环境对积水煤微观特性和氧化过程的影响

在深煤层和地热温度异常的矿井中，高地热环境会影响浸水煤的侵蚀过程。为了研究高地热环境对积水煤自燃的影响，在不同温度条件下（室温 20°C、40°C、60°C 和 80°C）将煤炭浸泡在水溶液中 30 天。利用低温氮吸附、红外光谱和同步热分析方法，研究了常温和高地热温度下涝煤样品微观理化结构的变化和氧化过程。与常温条件相比，高地热环境增加了积水煤中孔隙的数量和体积，破坏了分子间的氢键，增加了反应基团的总数。这些微观结构的变化影响了涝煤的氧化过程，导致 TG 和 DSC 曲线上的氧化特征温度点以及 TG 第二和第三阶段的活化能 E 明显低于常温条件下的涝煤。这项研究表明，高地热环境增强了涝煤的自燃倾向，加速了其氧化过程。

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来源期刊

Case Studies in Thermal Engineering Chemical Engineering-Fluid Flow and Transfer Processes

CiteScore

8.60

自引率

11.80%

发文量

812

审稿时长

76 days

期刊介绍： Case Studies in Thermal Engineering provides a forum for the rapid publication of short, structured Case Studies in Thermal Engineering and related Short Communications. It provides an essential compendium of case studies for researchers and practitioners in the field of thermal engineering and others who are interested in aspects of thermal engineering cases that could affect other engineering processes. The journal not only publishes new and novel case studies, but also provides a forum for the publication of high quality descriptions of classic thermal engineering problems. The scope of the journal includes case studies of thermal engineering problems in components, devices and systems using existing experimental and numerical techniques in the areas of mechanical, aerospace, chemical, medical, thermal management for electronics, heat exchangers, regeneration, solar thermal energy, thermal storage, building energy conservation, and power generation. Case studies of thermal problems in other areas will also be considered.