Abstract: Water in oil emulsion was used to capture CO₂ from biogas (CO₂/CH₄) under hydrate formation condition. Span 20 was used to disperse aqueous phase or hydrate in oil phase. The influences of temperature, feed gas composition, pressure and water cut on the separation efficiency of emulsion were investigated. The separation ability of the absorption-hydration hybrid method was much better than that of the single absorption separation method, and uniform and flowable hydrate slurry could be obtained. The separation ability of the emulsion system increased with decreasing temperature or increasing water cut in specific ranges. Taking into account both separation efficiency and flowability of the slurry, the suitable operation temperature, pressure and water cut were determined as 270.15—272.15 K, around 3.2 MPa and 20%—25%(vol), respectively. Under these conditions, after a two-stage separation, the content of CO₂ in vapor phase could be reduced from 31%(mol) to nearly 10%(mol), more than 87%(mol) CO₂ could be captured by the slurry.

Key words: biogas, oil-water emulsion, hybrid separation, hydrate

摘要： 研究了柴油-水乳液体系在水合物生成条件下对沼气（CO₂/CH₄）中CO₂的捕集能力。阻聚剂Span20被加入到乳液中以分散水滴和水合物颗粒。综合考虑了温度、原料气组成、压力和乳液含水率对柴油-水乳液体系分离能力的影响。从实验结果可以看出，吸收-水合耦合分离效果明显优于单独的吸收分离，且分离平衡后，浆液中水合物分散均匀，流动性良好。乳液体系分离能力在一定范围内随着温度降低和含水率的增加而增强。综合考虑乳液分离能力和流动特性表明，温度270.15～272.15 K，体系含水率 20%～25%（vol）和初始推动力为3.2 MPa左右时为最合适的分离条件，在对应条件下经过两级模拟分离，气相中CO₂浓度能从31%（mol）降到近10%（mol），超过87%（mol）的CO₂被水合物浆液捕集。

关键词: 沼气, 油-水乳液, 耦合分离, 水合物