关键词: 水合物形态, 堵塞机理, 二氧化碳水合物, 气团流, 段塞流

Abstract:

In order to clarify the formation morphologies and plugging mechanisms of carbon dioxide hydrate for intermittent flow, a high-pressure visual hydrate loop was used to carry out the formation experiment of carbon dioxide hydrate, and the formation and plugging morphology images of carbon dioxide hydrate under air mass flow and slug flow were analyzed. The results show that the main formation position of the hydrate under the air mass flow is the top of the pipeline, and the effective flow area is gradually reduced in the form of a continuously increasing hydrate layer, which eventually leads to pipeline plugging. Under the slug flow, hydrates are formed in large quantities in both the liquid phase and the top of the pipeline, but due to the erosion of large flow rate, the top hydrate layer can not exist for a long time. It breaks down into the main body of the liquid phase, resulting in the increase of the viscosity of the main body of the liquid phase, the increase of the flow resistance and the decrease of the flow velocity, thus providing conditions for the coalescence and agglomeration of flocculent hydrates in the liquid phase. The continuous accumulation of hydrate in liquid phase is the main reason for the hydrate plugging under slug flow. In addition, the hollow hydrate sphere formed under slug flow is a special hydrate form, which is mostly formed at the interface of liquid slug zone and liquid film zone. Because it is enclosed with gas, it will float in the upper part of liquid phase, and will be disturbed and broken into flaky hydrates, but these hydrates can not eventually gather and compact in the top space to form a dense hydrate layer.

Key words: hydrate morphology, plugging mechanism, carbon dioxide hydrate, air mass flow, slug flow