CO2突出危险煤层抽采瓦斯混合气水合分离产物特性的Raman光谱研究

Quantitatively obtaining the characteristics of hydrated-products of drained gas from coal and gas (CO2) outburst coal seam is important to the application of new separation technology based on hydrate. First, the Raman spectra of hydrated products are measured in-situ under the different gas components-concentrations, experimental temperatures-pressures, and surfactants samples-proportions, using confocal microscope Raman spectrometer system. Then, the crystal structures are determined based on the vibration modes of guest molecules and the loose-cage-tight-cage model. In addition, the cage occupancy ratio and hydration number are analytically determined from the van der Waals-Platteeuw model. The separation concentration of CO2 in hydrate phase is analyzed using polarization theory and Raman quantification factors. Moreover, the Raman characteristics of separated products, and the variations of the crystal structures, cage occupancy ratio, hydration number and the separation concentration, are investigated with the experimental conditions (including different gas components-concentrations, experimental temperatures-pressures, and surfactants samples-proportions). Finally, the technological conditions are optimized for coal mine gas with high CO2 concentration separation using hydrate technique. This study is very useful for illustrating the micro-mechanism of hydrated-products and for promoting the development of gas hydration separation and storage technique in depth. It is also significant to speed the CO2 capture, storage and utilization.

CO2突出危险煤层抽采瓦斯气分离产物特性的精确获取是水合分离新技术的应用关键。首先，利用可见显微共焦Raman实验平台原位测定瓦斯组分-浓度、实验温度-压力、添加剂种类-配比等条件下高CO2浓度瓦斯气水合分离产物特性的Raman光谱特征；继而，基于客体分子振动模式及“松笼-紧笼”模型确定水合物晶体结构，结合van der Waals-Platteeuw模型计算水合物孔穴占有率、水合指数，运用极化理论、Raman定量因子分析水合物相CO2分离浓度；进而，研究高CO2浓度瓦斯气水合分离产物显微Raman光谱特征及其晶体结构、孔穴占有率、水合指数、分离浓度等特性指标与气样组分-浓度、温度-压力、添加剂种类-配比等作用规律，优化高CO2浓度瓦斯气水合分离工艺条件。本研究对于阐明瓦斯气水合分离产物微观机理、推动瓦斯水合分离及储存新技术纵深发展、促进我国CO2捕集、利用及封存具有重要科学意义。

以我国甘肃窑街、吉林营城、和龙等CO2突出危险煤层瓦斯混合气分离与利用为背景，提出高 CO2 浓度瓦斯气水合分离方法，探索CO2 突出危险煤层抽采瓦斯气分离产物特性。据此，利用全透明水合物相平衡测定装置，采用观察法、图解法等判定方法测定了3种瓦斯混合气在纯水体系中水合分离相平衡参数；运用自主搭建的高CO2浓度瓦斯混合气水合分离产物特性Raman原位测试装置，获取了不同瓦斯气样、温度、压力影响下瓦斯水合分离产物拉曼光谱图，确定了水合物晶体中CO2伸缩振动和弯曲振动倍频的拉曼位移，以及CH4分子填充水合物的大孔穴和小孔穴的Raman位移，结合水合物“松笼-紧笼”模型等理论判断了瓦斯水合物晶体结构；基于Raman定量因子理论，利用Gaussian函数积分计算CO2与CH4的Raman谱峰面积，根据两者峰面积比值求出相应浓度比，绘制出高CO2浓度瓦斯混合气水合分离浓度标定曲线；结合van der Waals-Platteeuw模型等理论，计算了水合物孔穴占有率、水合指数等微观参数，发现在瓦斯气样不变、驱动力增加条件下水合物晶体大孔穴占有率始终远远大于小孔穴占有率，不同驱动力条件下小孔穴占有率值有明显差异，为了解瓦斯混合气体水合物的形成机制提供了有效识别方法；研究了THF、TBAB等热力学添加剂对高CO2浓度瓦斯气水合分离产物特性Raman光谱的影响，发现液面下部主要为TBAB半笼型水合物，且随着溶液中TBAB浓度增加，水合物相中CO2对应特征峰强度呈递增趋势，构建的半笼型水合物框架数量逐渐增加，为CO2分子提供更多可占据的笼型结构，高浓度TBAB有利于CO2分离与捕集；定性分析了TBAB-SDS体系中高浓度CO2瓦斯水合反应产物物性构成及晶体结构类型，揭示了TBAB-SDS体系中高浓度CO2瓦斯水合反应Raman光谱特征，阐释了热力学添加剂在高CO2浓度瓦斯混合气水合分离过程中对改善热力学工艺条件的作用机理。本研究成果为改进水合分离工艺条件、提高产品质量奠定理论基础。