Nguyen Ngoc N, Berger Rüdiger, Butt Hans-Jürgen
Physics at Interfaces, Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany.
School of Chemical Engineering, Hanoi University of Science and Technology, Dai Co Viet 1, Hanoi 100000, Vietnam.
ACS Appl Mater Interfaces. 2020 Mar 25;12(12):14599-14606. doi: 10.1021/acsami.0c00636. Epub 2020 Mar 13.
Resolving the long-standing problem of hydrate plugging in oil and gas pipelines has driven an intense quest for mechanisms behind the plug formation. However, existing theories of hydrate agglomeration have critical shortcomings, for example, they cannot describe nanometer-range capillary forces at hydrate surfaces that were recently observed by experiments. Here, we present a new model for hydrate agglomeration which includes premelting of hydrate surfaces. We treat the premelting layer on hydrate surfaces such as a thin liquid film on a substrate and propose a soft-sphere model of hydrate interactions. The new model describes the premelting-induced capillary force between a hydrate surface and a pipe wall or another hydrate. The calculated adhesive force between a hydrate sphere ( = 300 μm) and a solid surface varies from 0.3 mN on a hydrophilic surface (contact angle, θ = 0°) to 0.008 mN on a superhydrophobic surface (θ = 160°). The initial contact area is 4 orders of magnitude smaller than the cross-sectional area of the hydrate sphere and can expand with increasing contact time because of the consolidation of hydrate particles on the solid surface. Our model agrees with the available experimental results and can serve as a conceptual guidance for developing a chemical-free environmentally friendly method for prevention of hydrate plugs via surface coating of pipe surfaces.
解决油气管道中长期存在的水合物堵塞问题推动了对堵塞形成背后机制的深入探索。然而，现有的水合物团聚理论存在严重缺陷，例如，它们无法描述最近实验观测到的水合物表面纳米级的毛细作用力。在此，我们提出了一种新的水合物团聚模型，该模型包含水合物表面的预熔化现象。我们将水合物表面的预熔化层视为基底上的一层薄液膜，并提出了水合物相互作用的软球模型。新模型描述了水合物表面与管壁或另一个水合物之间由预熔化引起的毛细作用力。计算得出，一个水合物球体（直径 = 300 μm）与固体表面之间的粘附力在亲水性表面（接触角θ = 0°）上为0.3 mN，在超疏水性表面（θ = 160°）上为0.008 mN。初始接触面积比水合物球体的横截面积小4个数量级，并且由于水合物颗粒在固体表面的固结，接触面积会随着接触时间的增加而扩大。我们的模型与现有的实验结果相符，可为通过管道表面涂层开发一种无化学物质的环保型水合物堵塞预防方法提供概念指导。
