Numerical Simulations Of Gas Hydrate Crystal Growth

Gas hydrate form easily in multiphase subsea pipelines.And gas hydrate will lead to a decline of product quality,oil and gas pipelines blockage and equipment damage,which is a significant threat to the continued safety production and operation of piping system.In order to prevent gas hydrate formation and growth,Study on the growth law and the influencing factors of the gas hydrate crystal was carried out.Based on phase field theory,numerical simulation of the growth of CO₂ hydrate crystal after nucleation was carried on.A phase field model was established coupled with phase field,solute field and temperature field,and the anisotropy and a term of noise were introduced into the phase filed equation.And an explicit finite difference method was used to solve the phase field and solute field governing equation,and the alternating direction implicit method?ADI algorithm?was used to solve the temperature field equation.Then the discretization equation was embed in the program.And the image generation and displaying of numerical results were visualized by using drawing software and data analysis software.The numerical simulation results show that the noise,undercooling,anisotropy coefficient and interface thickness parameter all have effects on the growth of CO₂ hydrate crystal,including the crystal morphology,the dendrite tip velocity,solid fraction,solute and temperature distribution,etc.The noise relates the formation of the secondary dendrite branches and with the increasing of noise coefficient,the secondary branches are more greater.And with the increase of undercooling and anisotropy coefficient,the CO₂ hydrate crystal grows faster.With the increase of interface thickness parameter,the CO₂ hydrate crystal grows more slowly.Meanwhile,all the factors above have effects on the CO₂ hydrate crystal morphology.It's the first time to use the phase field method to study gas hydrate at home.Considering the temperature variation,study on the influencing factors of the gas hydrate crystal has been carried out.And a new way and theoretical basis is provided for further exploring and studying the gas hydrate crystal.