Simulation of Hydrate Particle Deposition in Horizontal Annular Mist Flow

Abstract

Summary In the prediction of hydrate deposition, few studies have considered the hydrate particles generated from droplets in the gas core, which makes it difficult to calculate the hydrate particle deposition accurately. Previous studies have introduced the effective deposition ratio (EDR) to predict the hydrate particle deposition from the gas core quantitatively, which simplifies the prediction process. However, a quantitative description of the EDR has not been studied. The current work has established a prediction model of hydrate particle deposition on a pipe wall and developed a method for solving the EDR based on the force analysis and removal mechanism (lifting, rolling, or slipping) of hydrate particles on the horizontal pipe wall in annular mist flow. The effects of gas velocity, pipe diameter, particle size, and other factors on the EDR of hydrate particles were analyzed using the optimized discrete particle model (DPM) in Fluent. The results show that the EDR is inversely proportional to the gas velocity under the comprehensive impacts of the turbulent kinetic energy and gas shear force. Under the influence of the liquid film "wrapping," the EDR rapidly grows and then stabilizes with the increase in particle size. Under the joint influence of the liquid film distribution and forces acting on the particles, the EDR first rapidly declines and then grows with the increase in pipe diameter, and finally tends to be stable. Through regression fitting of more than 700 sets of data, the empirical expression of the EDR of hydrate particles was established for the first time, and the error was within the allowable range in engineering. This work lays a foundation for the accurate calculation of hydrate particle deposition generated from droplets in a gas core.