摘要
深水天然气水合物是具有广阔应用前景的非常规天然气资源.开采出的深水天然气水合物通过管道输送是实现水合物资源开发、利用的关键环节.输送过程中,管道内的压力、温度会不断发生变化,使得管道内出现伴随水合物生长或分解的复杂气液固三相流动.本文介绍了天然气水合物资源分布情况和开采方式,综述了近年来天然气水合物生长、分解动力学和含水合物颗粒的气液固多相流动方面的研究进展,分析了深水天然气水合物输送管道的安全性.指出未来在深水水合物输送方面应坚持实验与理论相结合的研究手段,着重开展以下三个方面的研究内容:第一是考虑管流作用下天然气、水、水合物三相界面之间的传热传质特点,以及气液流速、流型对传热传质的影响,建立多组分气体水合物生长、分解动力学模型;第二是综合考虑水合物颗粒的微观受力和流体对固相的携带能力,分析水合物颗粒的聚集特征、流动特性以及在管道中的沉积规律;第三是考虑水合物颗粒的生长、分解与管道内流速、流型和压降之间的耦合作用,建立伴随水合物颗粒生长、分解、聚集、沉积的气液固多相管输模型,定量描述水合物颗粒的发展过程和三相流动规律,为深水天然气水合物输送管道的设计、运行和管理提供理论与技术支撑.
Gas hydrates are non-stoichiometric crystalline compounds that consist of host water molecules to form cages through hydrogen bond and hydrate formation gas molecules to fill inside, and thus stabilize the crystal lattice by weak van der Waals forces. Hydrate formation gas molecules, also called as guest molecules can be methane, ethane, propane, carbon dioxide and so on which are suitable in sizes for being adsorbed in water cages. Natural gas hydrates in deep water are the unconventional natural gas resources with wide development prospects. Pipeline transportation is the key point to realize the development and utilization of natural gas hydrate resources. During the transportation, the pressure and temperature in the pipelines would change continuously which lead to the complex gas-liquid-solid three-phase flow coupled with natural gas hydrates formation and decomposition. In this paper, research progress in four main aspects were analyzed which included the distribution conditions of natural gas hydrates resources in the world, the methods of exploitation, the kinetics of natural gas hydrates formation and decomposition and the gas-liquid-solid multiphase flow. Based on the four aspects, the safety of natural gas hydrate pipeline transportation in deep water was analyzed. Due to the special thermodynamic conditions of the natural gas hydrate transportation pipelines in deep water, it is common to observe the growth, dissociation, aggregation, deposition and other such kind of behaviors of hydrate particles. The flow regulation of this gas-liquid-solid multiphase is truly complicated and hardly well understood by us. What＇s more, the interaction of hydrate particle and multiphase flow increases the difficulty of predicting crucial flow parameters, such as flow patterns and pressure drop. Later research should insist on the combination of experiment and theory. More work should focus on the following three parts. The first part is establishing the formation and decomposition kinetic models for multi-component gas hydrate particles while taking the characteristics of mass and heat transfer in the natural gas, water and hydrate interfaces during the pipe flow into consideration, and involving the effects of gas, liquid flow rates and flow patterns on mass and heat transfer. The second part is to consider the forces on hydrate particles microscopically and the carrying capacity of the fluid comprehensively. Meanwhile, analyzing the aggregation and flow features and the deposition regularities of hydrate particles in pipelines. The last one is to establish a theoretical gas-liquid-solid multiphase flow model which includes the growth, decomposition, aggregation and deposition of hydrate particles. This model is supposed to reflect the coupling effects of hydrate particles＇ growth or decomposition with the flow rate, flow pattern and pressure drop of the pipelines. Consequently, the development of hydrate particles and the regularities of multiphase flow could be described quantitatively. This study provides the theoretical and technical foundations for the design, operation and management of natural gas hydrate transportation pipelines in deep water.
出处
《科学通报》
EI
CAS
CSCD
北大核心
2016年第22期2449-2462,共14页
Chinese Science Bulletin
基金
国家自然科学基金(51474184,51504206)
国家“十三五”重大科技专项(2016ZX05028-001-006)资助
关键词
天然气水合物
动力学
多相流
安全性
管道输送
natural gas hydrates, kinetics, multiphase flow, safety, pipeline transportation
