液相连续撞击流耦合鼓泡作用下天然气水合物生成过程机理

It is one key to store and transport natural gas via the hydrate technology that hydrate is rapidly produced on a large scale. The impinging stream technology is an advance in the process intensification field of the mass and heat transfer, which coefficients of the mass and heat transfers are more 5-10 times than that of the traditional chemical unit operations according to scientific or technical literatures. And bubbling is a common method to promote the formation of gas hydrate now.It is important to develop the technology of the natural gas storage and transportation via hydrate that the impinging stream and bubbling as a mechanical method can promote mass and heat transfers in the process of the gas hydrate formation..A set of special gas hydrate-forming system based on the liquid-continuous impinging stream and bubbling technology will be built in our application.The principle that natural gas hydrate is rapidly formed upon impinging streams and bubbling technology will be studied by experiment test and theoretical analysis.The hydrate-forming process will be observed and recorded using a high speed camera in real time. And the data with regard to the micro mixing and stress vibration being attributed to the impinging jet will be acquired by a strain measuring instrument of micro precision transducers and a X-ray stress meter.The microcosmic mechanism will be made clear about the act of breaking into fragents of hydrate film in the impinging field. The change process of the data such as temperature, pressure, quantity of flow, gas constituents and the mechanical strain of the impact resistant plane will be investigated on the process of hydrate formation in the system. And the microcosmic influence mechanism that the impinging jet promotes the rapid formation of gas hydrate in the hydrate-forming process will be clearly explained based on the molecular collision theory，the double-film theory, the surface renewal theory, the advanced crystallographic principle, crystallography and molecular dynamics simulation. The mathematical models will be set up about the reaction kinetics, the reaction thermodynamics and the heat and mass-transfers mechanism in the process of gas hydrate formation in the impinging jet and bubbling system according to the heat and mass transfer theories of multiple phase flows and the analytical method that was used to build the mathematical model about the reaction kinetics in the gas hydrate forming process by Peter Englezos. The application can seek for a new way to form rapidly natural gas hydrate and lay a theoretical foundation for the technology of the rapid formation of gas hydrate via impinging streams and bubbling.

水合物的规模化制备是天然气水合物储运技术产业化的关键之一。撞击流技术是多相反应过程强化领域内新进展，其强化传质传热能力达传统化工单元过程的5-10倍。鼓泡是强化水合物生成的传统方法。以液相撞击流耦合鼓泡强化水合物的生成对天然气固态储运技术发展具有重要的推动意义。.本项目拟通过实验测试和理论分析研究液相连续撞击流耦合鼓泡作用下天然气水合物生成过程机理。采用高速显微摄像仪实时记录水合物的微观生成过程，利用微型高精密传感器和X射线测量撞击流所产生的压力波动强度、撞击强度和微观混合程度。根据实验测试结果，结合分子碰撞理论、表面更新理论和结晶学原理，阐明撞击流耦合鼓泡强化天然气水合物快速生成的微观机理；借鉴多相流传递理论和Englezos水合物生成动力学模型的分析方法，建立液相撞击流耦合鼓泡作用下天然气水合物生成过程中的动力学、热力学和传质传热模型，为机械法促进天然气水合物快速生成技术提供理论支持

水合物快速生成技术是水合物法储运天然气技术产业化的关键步骤之一。天然气水合物的快速生成过程非常复杂，涉及气-液-固三相流动和反应过程，其间的质量和热量传递比较复杂。目前有关气体水合物的动力学研究和能够复验的动力学数据大多集中在水合物晶体生长阶段，气体水合物强化生成过程机理仍有待进一步研究。本项目主要研究液相连续撞击流耦合鼓泡作用下天然气水合物的生成过程机理，以期为机械扰动强化水合物生成过程提供基础理论支持。2014年9月开始通过实验测试构建和数值计算分析与模拟，课题组考察了液相连续撞击流耦合鼓泡反应器内气液固三相流动的多相流传递、反应器内CO2和CH4水合物的生成过程热力学和动力学，同时分析计算了甲烷水合物生成过程中的质量传递与撞击流强度之间的关系。实验测试发现，撞击流能够强化气体水合物的生成，随着撞击强度增加，甲烷气体消耗量也增加，二者近似呈直线增长关系，当撞击强度为72时，甲烷气体消耗速率为0.55mol/min。CO2气体实验测试得到了类似的结果，当撞击强度38时，CO2气体消耗速率为0.32mol/min。同时实验发现，撞击强度与水合物反应器的面积传质系数程高斯增长关系，通过数值分析给出了二者之间的数学关系式。