Numerical Simulation Of Mass Transfer And Heat Transfer Enhancement In Gas Hydrate Storage Tank

With the development of gas hydrate development and related technologies,the use of hydrate for natural gas solid storage and transportation has shown technical and economic advantages.However,hydrate formation is a reaction controlled by mass and heat transfer,so moving from laboratory scale to pilot or industrial scale cannot be achieved through direct scale-up.This paper uses Fluent software to study the hydrate reaction process in storage and transportation integrated gas storage tanks,simulating the enhanced process of mass and heat transfer in storage tanks,investigating the influence of gas inlet method,porous material and spiral coil structure on the hydrate storage process,and obtaining the optimal gas distributor and spiral coil structure.The results of the research will guide the design and scale-up of future hydrate reactors.The main points are summarized as follows:Firstly,an Fluent simulation method for mass transfer enhanced in gas hydrate storage tanks was established.The influence of different gas inlet modes,gas distributor hole shapes,inflow tubes and tube diameters on the mass transfer process in the storage tank was investigated.The results show that the rectangular hole gas distributor has the best mass transfer effect in the storage tank,which is better than the enhanced effect of circular holes,elliptical holes and guide tube on the gas distribution in the tank.The gas distribution uniformity of different gas distributor pipe diameters was compared under two inlet rates,showing that the gas distribution uniformity in the tank was the highest for the 45 mm gas distributor pipe diameter,with 0.993 and 0.99 respectively.The gas distributor outlet hole is therefore a rectangular hole with an optimum tube diameter of 45 mm.Secondly,a gas hydrate formation and heat transfer mathematical model,and the corresponding UDF program were established.Validation of a mathematical model of hydrate formation and heat transfer using the thermal conductivity of porous materials,showing an AARD of less than 6%and high model reliability.The simulations show that the higher the thermal conductivity of the porous material,the better the removal of the heat of hydration and the formation of hydrates.Finally,an Fluent simulation method for heat transfer enhanced in gas hydrate storage tanks was established.The effect of the radius of curvature and pitch of the enhanced heat transfer coil on the heat transfer process in the gas storage tank was investigated.The results show that the smaller the radius of curvature of the spiral coil,the better the heat transfer effect on the gas hydration reaction process in the storage tank,the higher the natural gas hydrate formation;And the larger the pitch,the better the heat transfer effect.The comprehensive evaluation results show that the spiral coil gas storage tank with a radius of curvature of 240mm and a pitch of 1.9(9(9₀ has the best effect on hydrate formation heat transfer,with a storage capacity of 140.20V/V.This Fluent model of hydrate formation and heat transfer can provide a theoretical basis for the further promotion and application of hydrate storage and transportation technology.