基于溶液内不同水合物相变过程热-质耦合原理分离合成气CO2的研究

A novel method is firstly proposed in this project to solve the difficulties, such as big enthalpy of gas hydrate phase change, multiphase flow, and heat and mass transfer during separating CO2 from reforming syngas using hydrate-based technology. The new separating technology is based on the interior heat and mass coupling when one hydrate forming and another hydrate dissociating coexist in the same solution. In this project, the hydrate-forming promoter and its aqueous solutions will be developed and optimized firstly based on hydrate phase equilibrium experiments and etc. Then, the formation and dissociation kinetics characteristics of different hydrates and and theirs mutual transformation kinetics, as well as the heat and mass coupling mechanisms during these hydrate transformation process, will be studied by hydrate kinetics experiments, Raman Spectroscopy, Molecular Stimulation and etc. The mechanisms that affecting on mass transfer of gas in gas hydrate slurry system will be studied by measuring the microstructure characteristic and rheological properties of gas hydrate slurry system. The high efficient gas-liquid mass transfer method and the hydrate rapid transformation method will be studied by the combination of physical and chemical enhancement. Finally, the separating processes and technologies are integrated and optimized by a continuous separation test. An integrated separation theoretical model will be established based on energy and mass equilibrium, gas hydrate phase equilibrium, gas-liquid mass transfer, and hydrates formation/dissociation kinetics based on heat and mass coupling when different hydrates formation and dissociation coexist in the same solution. The key issues involving in the new gas hydrate separation method, such as the hydrate-forming promoters and related solutions, the formation/dissociation kinetics mechanisms and mutual transformation kinetics of different hydrates and the heat and mass coupling mechanisms, the high efficient gas-liquid mass transfer mechanisms, and the rapid hydrate formation methods, will be solved through the implementation of this project. The research will establish a energy saving and high efficient CO2 hydrate separation technology, and will also provide theoretical and technical supports for the industrial application of this new method. The research results are significant to gas hydrate sciences, and will have a good application value in CO2 separation.

针对水合物法CO2分离相变潜热大，浆液流动与传热传质困难的难题，首次开展利用溶液内不同水合物形成分解过程热、质耦合原理分离合成气中CO2的研究。首先采用相平衡实验等研究优化水合物形成促进剂及溶液体系；然后采用动力学实验结合Raman光谱、分子模拟等研究不同水合物形成分解动力学特性及相互转化动力学影响机制，转化过程热、质耦合机制；通过浆液体系微观形貌、流变特性等研究气体传质机理及影响机制，研究强化气液高效传质与水合物快速转化的物理与化学方法；最后通过分离技术优化实验，建立基于质量平衡、能量平衡、水合物相平衡、气液传质、不同水合物形成分解热-质耦合动力学的分离过程理论模型。解决最佳促进剂溶液，不同水合物形成分解动力学机理、相互转化动力学及其热、质耦合机制，气液传质机理及水合物快生成方法等关键问题。为建立节能高效CO2水合物分离技术及其应用提供理论和技术支持，具有重要科学意义和应用价值。

针对水合物法CO2分离相变潜热大，浆液流动与传热传质难题，开展了不同水合物相变热、质耦合分离IGCC合成气中CO2的研究；采用实验和理论模拟等方法系统研究了新型水合物形成促进剂、水合物分离热力学、动力学、分离过程阻聚、强化传热传质、水合物快速形成技术及热-质耦合分离新技术等。（1）建立了溶质空穴理论与前沿分子轨道分析、分子动力学模拟、PXRD和Raman分析综合研究新型水合物形成促进剂的新方法，阐明了TBAB促进水合物形成的机理，研发了TBAB+DMSO、TBAB+TMS等高效促进剂，符合水合物热质耦合分离要求，测定了水合物分离相平衡数据，阐明了其影响机制，建立了热力学理论模型。（2）阐明了TBAB/CO2/H2水合物微观生长规律，CO2填充对TBAB水合物结构稳定机制与纯TBAB水合物及TBAB/CO2混合水合物相互转化机理，阐明了水合物形成分解驱动力、传热与传质速率对合成气水合物分离的影响机制，揭示了气液相间CO2传递是IGCC水合物快速形成的控制步骤，建立了水合物分离动力学理论模型。（3）建立了化学强化和物理强化相结合提高水合物分离速率的方法，揭示了CO2增溶剂DMSO和TMS的增效机理，研发了椰油酰胺类高效水合物阻聚剂，显著提高了水合物分离速率和分离效果，阐明了其阻聚机理；研发了纳米Al2O3耦合TBAB溶液、13X分子筛负载TBAB溶液和温度扰动提高水合物成核速率、气液接触传质效率和分离效率的强化方法，建立了基于鼓泡法和高速旋流喷射水合物快速形成技术及实验装置，阐明了分离过程特性和影响机制。（4）建立了基于溶液内纯TBAB水合物与TBAB+CO2混合水合物相变热-质耦合原理连续分离IGCC合成气中CO2的新工艺，阐明了分离特性及影响机制，分离过程温度与TBAB浓度波动明显降低，分离能耗降低、操作弹性提高，CO2分离系数和分离因子分别达到0.8和8.15。为建立节能高效CO2水合物分离技术及其应用提供了理论和技术支持，具有重要科学意义和应用价值。