基于Raman光谱的温度调控下瓦斯水合分离动力学研究

Kinetics of gas hydrate separation process and separation efficiency are more sensitive to temperature-pressure condition. The gas separation based on hydrate is a dynamic process with varied gas concentration and temperature-pressure condition. The dynamic temperature regulation method is proposed to examine the temperature effect on kinetics in gas separation based on hydrate, in the aim of promoting the gas hydration rate and increasing the separation concentration. Accordingly, the temperature regulation schemes are determined using the phase equilibrium theory. The gas/hydrate phase behavior are investigated by in-situ Raman Spectroscopy-GC system. Then the hydration rates of gas component are achieved based on Raman spectra quantitative factor to address the mass transfer rules of gas components during separation under temperature regulation condition. Specifically, the variation relations of Raman intensity, cage occupancy ratio, hydration number and the separation concentration are elucidated combined with the Raman unified strength theory and van der Waals-Platteeuw model within this study. Furthermore, kinetic model for gas separation is developed based on Chen-Guo model, with the model parameter obtained. The kinetic rate equation is deduced to reveal the mechanism of temperature regulation on the kinetic response during gas separation based on hydrate. This study has significant scientific implications and engineering value in promoting gas separation techniques based on hydrate.

温压条件显著影响瓦斯水合分离动力学进程及分离效果。针对分离过程瓦斯浓度、温压参数动态变化的特点，以“提速增浓”为目的，提出分离过程温度动态调控方法，探索其影响下瓦斯水合分离动力学规律。为此，利用瓦斯水合分离Raman-GC原位实验系统，结合水合物相平衡理论确定温度调控方案，测定分离过程气相、水合物相微观变化的Raman光谱信息；基于Raman光谱定量因子计算瓦斯组分水合速率，阐明温度调控下分离过程瓦斯组分物质传递规律；结合 Raman 强度归一化理论、van der Waals-Platteeuw模型，确定温度调控下谱峰强度、孔穴占有率、水合指数、分离浓度等变化关系；基于Chen-Guo水合物理论，建立瓦斯水合分离动力学模型，对模型参数关联求解，获得瓦斯组分水合动力学速率方程，揭示温度调控等因素对瓦斯水合分离动力学影响机理。该研究对于推动瓦斯水合分离技术发展具有重要科学意义和工程价值。

依据多元瓦斯水合物相平衡理论模型获得各种类瓦斯气样水合分离相平衡条件，设定不同推动力条件；利用气相色谱仪在线测定不同水合反应时刻气相组分浓度，基于多元瓦斯水合物相平衡理论计算该时刻体系相平衡参数，得到该时刻实验体系温度调控值，开展温度调控影响下瓦斯水合分离实验研究。基于Raman强度归一化理论，利用Gaussian/ Lorentzian函数拟合计算出不同时刻气相组分Raman谱峰面积，结合该时刻气相色谱浓度测定值，计算出该反应时刻温度压力条件下Raman光谱相对定量因子；结合不同反应时刻水合物相晶体孔穴谱图面积，基于Raman光谱相对定量因子与反应体系温度-压力变化曲线，分析出温度调控下瓦斯混合气中各气体组分水合速率，获取温度调控等因素影响下瓦斯水合分离过程各组分物质传递规律。基于水合分离结束水合物相Raman谱图，结合客体分子振动模式、Raman位移数据及水合物“松笼-紧笼”模型等理论，确定瓦斯水合物晶体结构；基于Raman光谱相对定量因子，依据van der Waals-Platteeuw模型，计算出孔穴占有率、水合指数、目标组分浓度等分离效果参数变化，分析温度调控、瓦斯组分浓度、推动力等因素对水合物相晶体中客体分子谱峰强度、孔穴占有率、水合指数等影响规律。以气体水合物形成理论为基础，建立了推动力与气体消耗速率相关联的瓦斯水合分离动力学模型；结合实验所得瓦斯气体组分、浓度变化及温度-压力曲线，获得瓦斯气体水合速率方程，据此分析出了温度调控、气体组分浓度、推动力等因素对瓦斯水合分离动力学影响机理。