Effect of low-temperature pre-oxidation on microstructure and reignition characteristic of water-immersion lignite

IF 3 3区 工程技术 Q2 CHEMISTRY, ANALYTICAL Journal of Thermal Analysis and Calorimetry Pub Date : 2024-09-03 DOI:10.1007/s10973-024-13579-6
Wei Zhang, Deming Wang, Haihui Xin, Zhenhai Hou, Chenguang Wang, Zuoming Xu, Zhangfan Qi, Jian Gan
{"title":"Effect of low-temperature pre-oxidation on microstructure and reignition characteristic of water-immersion lignite","authors":"Wei Zhang, Deming Wang, Haihui Xin, Zhenhai Hou, Chenguang Wang, Zuoming Xu, Zhangfan Qi, Jian Gan","doi":"10.1007/s10973-024-13579-6","DOIUrl":null,"url":null,"abstract":"<p>The residual coal is prone to oxidation in different degrees after being immersed-dried in waterlogged goafs, but the reignition characteristics of water-immersion coal by low-temperature pre-oxidation remain unclear. Herein, lignite was pre-oxidized to 40 °C, 80 °C, 120 °C, 160 °C, 200 °C, and 230 °C after 60 days of immersion. Moreover, the microstructure changes of water-immersed lignite after oxidized were investigated using low-temperature nitrogen adsorption and infrared spectroscopy, and its spontaneous combustion characteristics were assessed employing thermogravimetry. The results displayed that the pore volume, specific surface area, and pore diameter increased and then decreased as the pre-oxidation temperature rose. Specifically, lower temperatures (below 80 °C) promoted the formation of micropores and mesopores, as well as the merger and transformation of pores into macropores, which facilitates the diffusion and adsorption of oxygen. However, higher temperature oxidation (&gt; 200 °C) reduced both the number of pores and the content of reducing functional groups (–OH, –CH<sub>3</sub>, and –CH<sub>2</sub>). Comparatively, the lignite oxidized at 80 °C maintained a strong chemical reactivity owing to the high relative content of -CH<sub>2</sub> and C = O. Furthermore, the pre-oxidation treatment mainly affected the thermal decomposition and gas-phase combustion of the water-immersed coals. Moreover, as the degree of oxidation rose, the characteristic temperatures (T<sub>2</sub>–T<sub>4</sub>) and the activation energy first decreased and then increased, while the comprehensive combustion index exhibited an opposite trend. Notably, the critical oxidation temperature of 80 °C is a turning point for the above change. Thus, the pre-oxidation at 80 °C heightens the risk of reignition in water-immersion coal owing to its developed pore structure and abundant active groups. It is imperative to avoid the critical temperature during low-temperature oxidation of water-immersed coals.</p>","PeriodicalId":678,"journal":{"name":"Journal of Thermal Analysis and Calorimetry","volume":null,"pages":null},"PeriodicalIF":3.0000,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Thermal Analysis and Calorimetry","FirstCategoryId":"5","ListUrlMain":"https://doi.org/10.1007/s10973-024-13579-6","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, ANALYTICAL","Score":null,"Total":0}
引用次数: 0

Abstract

The residual coal is prone to oxidation in different degrees after being immersed-dried in waterlogged goafs, but the reignition characteristics of water-immersion coal by low-temperature pre-oxidation remain unclear. Herein, lignite was pre-oxidized to 40 °C, 80 °C, 120 °C, 160 °C, 200 °C, and 230 °C after 60 days of immersion. Moreover, the microstructure changes of water-immersed lignite after oxidized were investigated using low-temperature nitrogen adsorption and infrared spectroscopy, and its spontaneous combustion characteristics were assessed employing thermogravimetry. The results displayed that the pore volume, specific surface area, and pore diameter increased and then decreased as the pre-oxidation temperature rose. Specifically, lower temperatures (below 80 °C) promoted the formation of micropores and mesopores, as well as the merger and transformation of pores into macropores, which facilitates the diffusion and adsorption of oxygen. However, higher temperature oxidation (> 200 °C) reduced both the number of pores and the content of reducing functional groups (–OH, –CH3, and –CH2). Comparatively, the lignite oxidized at 80 °C maintained a strong chemical reactivity owing to the high relative content of -CH2 and C = O. Furthermore, the pre-oxidation treatment mainly affected the thermal decomposition and gas-phase combustion of the water-immersed coals. Moreover, as the degree of oxidation rose, the characteristic temperatures (T2–T4) and the activation energy first decreased and then increased, while the comprehensive combustion index exhibited an opposite trend. Notably, the critical oxidation temperature of 80 °C is a turning point for the above change. Thus, the pre-oxidation at 80 °C heightens the risk of reignition in water-immersion coal owing to its developed pore structure and abundant active groups. It is imperative to avoid the critical temperature during low-temperature oxidation of water-immersed coals.

Abstract Image

查看原文
分享 分享
微信好友 朋友圈 QQ好友 复制链接
本刊更多论文
低温预氧化对水浸褐煤微观结构和复燃特性的影响
残留煤炭在浸水干燥后易发生不同程度的氧化,但低温预氧化对浸水煤炭的复燃特性尚不清楚。在本文中,褐煤在浸水 60 天后分别被预氧化至 40 ℃、80 ℃、120 ℃、160 ℃、200 ℃ 和 230 ℃。此外,还利用低温氮吸附和红外光谱法研究了氧化后水浸褐煤的微观结构变化,并利用热重法评估了其自燃特性。结果表明,随着氧化前温度的升高,孔隙体积、比表面积和孔径先增大后减小。具体来说,较低的温度(低于 80 °C)促进了微孔和中孔的形成,以及孔隙向大孔隙的合并和转化,这有利于氧气的扩散和吸附。然而,更高的氧化温度(> 200 °C)会减少孔隙的数量和还原官能团(-OH、-CH3 和 -CH2)的含量。相比之下,在 80 °C 下氧化的褐煤由于 -CH2 和 C = O 的相对含量较高而保持了较强的化学反应活性。此外,预氧化处理主要影响水浸煤的热分解和气相燃烧。此外,随着氧化程度的升高,特征温度(T2-T4)和活化能先降低后升高,而综合燃烧指数则呈现相反的趋势。值得注意的是,80 °C 的临界氧化温度是上述变化的转折点。因此,由于水浸煤的孔隙结构发达,活性基团丰富,80 ℃的预氧化会增加水浸煤的复燃风险。因此,在水浸煤的低温氧化过程中,必须避开临界温度。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 去求助
来源期刊
CiteScore
8.50
自引率
9.10%
发文量
577
审稿时长
3.8 months
期刊介绍: Journal of Thermal Analysis and Calorimetry is a fully peer reviewed journal publishing high quality papers covering all aspects of thermal analysis, calorimetry, and experimental thermodynamics. The journal publishes regular and special issues in twelve issues every year. The following types of papers are published: Original Research Papers, Short Communications, Reviews, Modern Instruments, Events and Book reviews. The subjects covered are: thermogravimetry, derivative thermogravimetry, differential thermal analysis, thermodilatometry, differential scanning calorimetry of all types, non-scanning calorimetry of all types, thermometry, evolved gas analysis, thermomechanical analysis, emanation thermal analysis, thermal conductivity, multiple techniques, and miscellaneous thermal methods (including the combination of the thermal method with various instrumental techniques), theory and instrumentation for thermal analysis and calorimetry.
期刊最新文献
Thermal characterization of plat heat exchanger made from polymer biocomposite reinforced by silicon carbide Recent advances in thermal analysis and calorimetry presented at the 3rd Journal of Thermal Analysis and Calorimetry Conference and 9th V4 (Joint Czech–Hungarian–Polish–Slovakian) Thermoanalytical Conference (2023) Spalling behavior of high-strength polypropylene fiber-reinforced concrete subjected to elevated temperature Study of thermal behavior and crystallization kinetics of glass microspheres in the Y3Al5O12-Al2O3 system Size fraction characterisation of highly-calcareous and siliceous fly ashes
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
0
微信
客服QQ
Book学术公众号 扫码关注我们
反馈
×
意见反馈
请填写您的意见或建议
请填写您的手机或邮箱
已复制链接
已复制链接
快去分享给好友吧!
我知道了
×
扫码分享
扫码分享
Book学术官方微信
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术
文献互助 智能选刊 最新文献 互助须知 联系我们:info@booksci.cn
Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。
Copyright © 2023 Book学术 All rights reserved.
ghs 京公网安备 11010802042870号 京ICP备2023020795号-1