Experimental Study On Erosion And Wear Of Elbows Of Natural Gas Gathering And Transportation Pipelines

In the sand-produced gas field(such as the shale gas field),the wellhead flow from the reservoir will carry a certain mass of solid impurities like debris and cuttings.Gas gathering system often operates preliminary sand at well field;but limited to the effect of the equipment,inevitably,gathering pipeline carries some residual fine particles,which been deeply separated at the united station.As a consequence,it will cause erosion to the 90 degree elbow which is a common component of pipeline system.Therefore,aiming at the problem of 90 degree elbow erosion under gas gathering condition,this paper uses the method of CFD numerical simulation and indoor experimental loop,studies on the transient and steady-state behavior of elbow erosion from different aspects.At the stage of numerical simulation,the geometric model of the elbow is established and the grid independence is checked.After the establishment of erosion predict controller,several influence factors of the 90 degree elbow are analyzed by single variable controlled method.This paper chooses Peng-Robinson gas state equation and RNG K-? turbulence model to describe the gas main fluid;Tulsa erosion predicting model to indicate erosion behavior.The tendency of erosion rate with the influence factors is studied by changing the setting value of certain parameters singly.At the stage of indoor experiment,author design and build a complete set of solid circulated-gas unidirectional flow experimental device with geometric scale 1:1 to the DN150 gathering pipeline is established,which covers an area of 2550 mm× 10000 mm ×5200 mm and performs different airflow directions of elbow.This device carries out 0-50 m/s gas fluid and 0.15-5.0mm particles equipment.With air carrying natural quartz sand to simulate gas carrying particles and causing elbow erosion.The 0.001mm ultrasonic thickness gauge is used in the experiment detecting elbow surface thinning under different economic gathering velocity in different direction of gravity.Used SEM scanning electron microscope to observe metal erosion surface morphology.Coloring the inner wall of elbow to study theory of erosion evolution.In this study,some important points are obtained:the distribution of erosion area on elbow under different gravity directions;The effect of the gas velocity flow rate on the erosion rate and the erosion mechanism under the economic gathering velocity;The influence of gathering pressure on elbow erosion and erosion distribution;The erosion severity of commonly used diameters;The influence of different sizes of particles on erosion distribution,and draw the erosion area genealogy;Elbow erosion evolution theory based on the mass of the cumulative scour.At last,it is pointed out that the gas gathering and transportation system should keep a low flow velocity;The use of wall thickening process at the elbow is a practical solution to reduce erosion wear.