Aggregation behavior analysis of hydrate particles in the bend pipe based on the population balance model

The hydrate particle aggregation is crucial for the flow safety of oil and gas pipelines. In this paper, coupled with the Eulerian-Eulerian model, k−ε turbulence model and the population balance model considering the hydrate aggregation and breakage, the hydrate aggregation process is studied in the bend, and the change of the average particle size under different hydrate volume fractions is discussed. The results show that the hydrate aggregation process includes two stages in the bend, namely the rapid growth and the dynamic equilibrium. In the rapid growth stage, both the hydrate concentration and particle size in the elbow increase rapidly, and the high concentration and large particle size regions on the inside of the elbow also increase significantly. Furthermore, two types of aggregates are formed on the inside of the elbow. One is a small amount of large-particle aggregates, while the other is the relatively high concentration of medium-size aggregates. Besides, the uniform suspension with a smaller concentration and particle size is distributed on the outside of the elbow, but there are also large-size particles that aggregate and adhere near the wall of pipe. As the hydrate volume fraction increases, the hydrate average particle size increases. High concentration hydrate reaches dynamic equilibrium faster during the flow process.