Abstract: Natural gas hydrate，which deposits on the ocean floor or in permafrost regions in vast quantities, is a potential future energy resource. The method by depressurization is known to be adopted for large scale exploitation natural gas hydrates. The heat transfer boundary can affect overly hydrate dissociation rate. Investigated these control mechanisms, built one two-dimensional model, and analyzed the change of temperature,pressure,hydrate saturation and cumulative gas produced under the influences of different heat transfer boundary conditions. The calculation results show that natural gas hydrates exploited by depressurization need heat transferred from surroundings. The amount of gas produced at adiabatic condition is only 1/36 to that of gas produced in complete decomposition. With higher temperature at boundary, hydrate decomposes more rapidly, decomposition rate at boundary temperature 277.45 K is 2.5 times as much as that at 275.45 K, and gas generated rate is greater, but the magnitude of heat makes a minor effect on cumulative gas produced.

Key words: Natural gas hydrate , Depressurization ,  Control mechanisms ,  Heat transfer analysis

摘要： 天然气水合物广泛存在于海底和冻土等极地环境中, 是未来潜在的新型天然气能源。降压开采天然
气水合物适合于大规模工程应用, 边界传热是影响天然气水合物分解速度的重要因素。研究了天然气水合物降压
开采的控制机理, 建立了二维开采模型, 分析了实验室小尺度下不同边界传热条件对天然气水合物降压开采过程中
温度、压力、饱和度以及产气率变化的影响。结果表明, 水合物降压开采需要边界能量输入, 边界绝热时产气总量为
完全分解时的1/ 36 , 边界温度越高, 水合物分解越快, 边界温度为277.45 K 时分解速度为275.45 K 时的2.5 倍, 产
气率越快, 但对产气总量影响不大。

关键词: 天然气水合物 , 降压开采 , 控制机理 , 传热分析