煤层亚临界/超临界CO_(2)吸附特征与封存模式  

Adsorption characteristics and storage models of subcritical/supercritical CO_(2) in coal seams

作　　者：王帅峰 韩思杰[2,3] 桑树勋[1,2,3] 郭常建 郭庆 徐昂 张金超 WANG Shuaifeng;HAN Sijie;SANG Shuxun;GUO Changjian;GUO Qing;XU Ang;ZHANG Jinchao(School of Resources and Geosciences,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China;Jiangsu Key Laboratory of Coal-Based Greenhouse Gas Control and Utilization//China University of Mining and Technology,Xuzhou,Jiangsu 221116,China;Carbon Neutrality Institute,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China)

机构地区：[1]中国矿业大学资源与地球科学学院 [2]江苏省煤基温室气体减排与资源化利用重点实验室·中国矿业大学 [3]中国矿业大学碳中和研究院

出　　处：《天然气工业》2024年第6期152-168,共17页Natural Gas Industry

基　　金：国家自然科学基金青年项目“煤岩注入CO_(2)吸附置换CH_4过程与机理的模拟研究”(编号:42102207);国家自然科学基金碳中和专项“CO_(2)地质封存潜力与能源资源协同理论方法体系及其应用基础”(编号:42141012);江苏省大学生创新训练计划项目“深部煤层超临界CO_(2)地质封存潜力评价方法研究”(编号:202310290233Y);中央高校基本科研业务费专项项目“火力电厂烟气CO_(2)咸水层封存有效性与安全性理论”(编号:2023KYJD1001)。

摘　　要：大规模高效CO_(2)地质封存是短期内快速实现CO_(2)减排的关键途径之一,以吸附特征为主要封存机制的深部不可采煤层CO_(2)封存具有规模化实施的潜力。为研究深部煤层CO_(2)封存机制,以沁水盆地无烟煤为研究对象,开展了高温高压CO_(2)吸附实验,并采用简化局部密度模型(SLD-PR)拟合,分析了温压变化下不同孔隙的吸附相密度分布特征,揭示了以吸附相密度和最大吸附层厚度协同变化为核心的煤层CO_(2)封存机理,最后通过准确划分孔内吸附空间与自由空间,预测了不同埋深下煤层CO_(2)封存量。研究结果表明:(1)不同温度下超临界CO_(2)吸附曲线均表现出典型的超临界气体吸附特征,过剩吸附量(最大值介于1·25~1·75 mmol/g)在达到最大值后下降;(2)孔隙内CO_(2)吸附层分为接触层、内层和过渡层,亚临界CO_(2)在孔内以单分子层吸附为主,而超临界CO_(2)吸附方式为多分子层吸附;(3)最大吸附层厚度随埋深增加而减小,与温度呈正相关,而与压力呈负相关;(4)CO_(2)平均吸附相密度随埋深“先增后减”,总封存量与绝对吸附量曲线在CO_(2)处于超临界状态下存在差异。结论认为:(1)在吸附空间与吸附相密度协变下,煤层CO_(2)微观封存模式随埋深可分为亚临界单分子层吸附、超临界类气态多分子层吸附型以及超临界类液态多分子层吸附3种类型,自由相封存量对总封存量的贡献随埋深增加,但吸附封存仍是煤层CO_(2)封存的主要方式;(2)研究成果揭示了原位煤层超临界CO_(2)封存机理,能够为深部煤层CO_(2)封存能力评价提供新认识。Large-scale efficient CO_(2) geological storage is one of the key means to realize CO_(2) emission reduction rapidly in a short term.CO_(2) storage in deep unminable coal seams with adsorption as the main storage mechanism has the potential of large-scale implementation.In order to study the mechanisms of CO_(2) storage in deep coal seams,this paper carries out a high-temperature and high-pressure CO_(2) adsorption experiment on the anthracite coal taken from the Qinshui Basin.Then,the SLD-PR model is used for fitting,the adsorption density distribution characteristics of different pores with the variation of temperature and pressure are analyzed,and the CO_(2) storage mechanisms in coal seams with the collaborative change of adsorbed phase density and maximum adsorption layer thickness as the core are revealed.Finally,the volumes of CO_(2) storage in coal seams at different burial depths are predicted by classifying adsorption space and free space in pores accurately.And the following research results are obtained.First,the adsorption curves of supercritical CO_(2) at different temperatures all present the typical adsorption characteristics of supercritical gas,with the excessive adsorption capacity(the maximum value ranging from 1.25 to 1.75 mmol/g)decreasing after reaching the maximum value.Second,the CO_(2) adsorption layers in pores are divided into contact layers,inner layers and transition layers.In pores,subcritical CO_(2) is mainly in the mode of monomolecular layer adsorption,while supercritical CO_(2) is in the mode of multi-molecular layer adsorption.Third,the maximum adsorption layer thickness decreases with the increase of burial depth,and it is in positive correlation with temperature and negative correlation with pressure.Fourth,the average CO_(2) adsorbed phase density increases firstly and then decreases with burial depth,and the total storage and the absolute adsorption curves are different when CO_(2) is in the supercritical state.In conclusion,under the collaborative change of adsorption spac

关 键 词：超临界 CO_(2) 深部煤层 吸附相密度分布 SLD-PR模型 最大吸附层厚度 封存容量 吸附封存 

分 类 号：TQ171.9[化学工程—玻璃工业]