吸附-水合耦合作用下低浓度煤层气的提纯特性及气体分子传输机理研究

Utilizing the low-concentration coalbed methane (CBM) efficiently is very important to optimize the energy structure and protect the atmosphere environment. The gas hydrate based separation technology is a promising technology for the purification of low-concentration CBM due to its advantages of high gas storage capacity and energy saving, etc. However, shortening the hydrate formation process and increasing CH4 recovery is a key issue that should be solved. In this research, a novel method that couples gas hydrate formation and CH4 adsorption of the carbon-based porous materials is proposed to increase the CH4 separation efficiency. However, knowing the separation properties of the low-concentration CBM and the mechanism of mass transfer of different gas molecules (CH4, N2, and O2) in the carbon-based porous materials is the key scientific issue that should be urgently solved for the optimization of this hybrid adsorption-hydrate formation method. This research will use a multi-scale research method that combines macroscopic experiments and microscopic in situ Raman spectroscopy to study the characteristics of CH4 adsorption in the carbon-based porous materials, the kinetics of low-concentration CBM purification in the carbon-based porous materials, and the mechanism of mass transfer of different gas molecules during the separation process. Therefore, the factors that influence the mass transfer of gas molecules in the hybrid adsorption-hydrate formation process will be revealed, the competing mechanism between N2/O2 and CH4 molecules will be elucidated, and the experimental and theoretical approaches to increase CH4 recovery and purification rate will be obtained. These results will lay a theoretical foundation to accelerate the development of the low-concentration CBM separation technology.

高效利用低浓度煤层气对优化能源结构、保护大气环境具有重要意义。利用水合物技术提纯低浓度煤层气有良好的应用前景，具有储气率高、节约能耗等优点，其中缩短水合物结晶过程、提高CH4回收率是解决问题的关键。本项目提出将水合作用与煤基多孔炭材料富集CH4的吸附作用相耦合的新型提纯方法，用来提高CH4分离效率。揭示煤基多孔炭材料氛围的煤层气提纯特性以及不同气体分子（CH4,N2,O2）的传质规律是优化该方法急需解决的关键科学问题。本项目采用宏观特性研究与微观原位拉曼光谱测试相结合的多尺度方法研究煤基多孔炭材料对CH4的吸附特性、煤层气在煤基多孔炭材料氛围的提纯动力学特性，以及不同气体分子在提纯过程的传输机理，从而揭示气体分子在吸附-水合耦合作用下的传质影响因素及其作用规律，阐明N2/O2与CH4的竞争机制，得出提高CH4回收率和提纯速率的实验与理论方法，为推动低浓度煤层气提纯技术的发展奠定理论基础。

高效利用低浓度煤层气对优化能源结构、保护大气环境具有重要意义。利用气体水合物技术提纯低浓度煤层气有良好的应用前景，具有储气率高、节约能耗等优点。如何提高水合物的结晶生长速率、CH4回收率和提纯效率是该技术需解决的关键科学问题。本项目首次提出了将气体水合作用与碳基多孔纳米材料对CH4的吸附作用相耦合的学术思路，促进气体水合物的结晶生长并提高CH4提纯效率。①热力学特性研究。采用高压三维微量热扫描法获得了CH4+N2+O2、CH4+CO2、CO2等多种气体在不同热力学添加剂体系形成水合的相平衡条件以及水合物分解焓在不同添加剂体系的变化规律；②动力学特性研究。发现了低浓度煤层气在不同添加剂溶液体系（TBAC、TBAB）的提纯特性，获得了不同类型的碳基多孔纳米流体的制备方法，揭示了吸附-水合耦合作用下CH4水合物在碳基多孔纳米流体中的结晶机理，阐明了诱导时间、气体消耗量、储气量在不同浓度纳米石墨流体中的变化规律。探明了吸附-水合耦合作用下低浓度煤层气在碳基多孔纳米流体中的提纯特性以及煤层气提纯过程中不同气体分子的传输机理。③气体分子竞争机理研究。采用高压原位拉曼光谱法从分子尺度探明了低浓度煤层气提纯过程中CH4、N2、O2等不同气体分子竞争机理。④低浓度煤层气提纯的经济性分析。根据实验研究结果设计了三种水合物法提纯低浓度煤层气的工艺流程，分别对不同工艺流程进行了㶲分析，探明了操作条件（温度、压力、添加剂浓度等）对㶲效率的影响，建立了㶲经济学模型，综合分析了提纯系统中各个能源装置的经济性能，为水合物法提纯低浓度煤层气技术的工业生产提供了理论参考依据。项目执行期间，在国际期刊发表SCI检索论文11篇（SCI一区论文8篇、SCI二区论文2篇、SCI三区论文1篇），出版学术专著1部；授权发明专利1项、申请发明专利1项；参加国国际学术会议5次，在国际学术会议作大会特邀报告3次，在国内学术会议作大会特邀报告1次；培养博士研究生2名、硕士研究生6名、省部级青年拔尖人才1名。