Structure Improvement And Desanding Performance Study Of Slug Catcher

Sand production in the offshore gas condensate field is widespread,which seriously threatens the normal operation of the downstream production equipments.As the traditional separation equipment being difficult to be transplanted directly to the small offshore platform,in this paper,some improvements are made to the traditional slug catcher,including the pre-separation cyclone set in the inlet,and the internal baffles used to trap sand.Thus,the sand is trapped in the slug catcher and then being removed.Based on the theory of cyclone separation and sedimentation tank,the separation mechanism of cyclone separator was studied by numerical simulation method,while the separation performance of slug catcher was systematically evaluated by experimental test method.The main contents and conclusions are as follows:The tangential velocity of the cyclone field is divided into the wall area,the quasi-free zone and the forced vortex zone.The maximum tangential velocity in the radial direction locates at about 2/3 of the exhaust pipe diameter.The distribution of tangential velocity in the axial direction is similar to the“U”type,indicating the tangential velocity being low in the center,but high on the edge of the separator.The axial velocity is divided into the two parts:the upstream flow in the axis-center and the downstream flow around the pipe wall.The velocity decreases with the attenuation of axial energy,when deceleration and even stagnation flow appear in the upstream flow center.The spatial distortion and helix radius of the zero envelope can reflect the sTableility of the flow field and the swirl intensity.Increasing the cone height,shrinkage distance and reducing the cylinder height of the cyclone,the tangential flow velocity in the cyclone increases,and the particle separation efficiency increases as well.The radial shrinkage of the zero envelope enhances the spiral of flow field,and leads to the transformation between the different states?circular truncated cone,cylinder cone,and circular cone?,and therefore increasing the energy loss.The range analysis shows that the factors influencing the separation performance of the trap?slug catcher?are the particle size,liquid level of the slug catcher and the inlet flowrate.Orthogonal experimental analysis indicates that the particle size has the most significant effect,while the other two are not of great significance.The slug catcher with baffle sets in which the distance ratio L₁/L0>0.55 and the height ratio H₁/D>0.37,tends to be in the high efficiency area,where the separation efficiency is about 95%,and the critical particle size is reduced to about 10?m.The cyclone is able to effectively separate the droplets and sand particles carried by the gas,resulting in an incremental pressure drop of only 0.0415.An air flowrate fluctuation within±20%of the range has little effect on the separation.However,±20%fluctuation of the fluid flowrate deteriorates the separation,and the critical particle size increased to about 40?m.Only when the first baffle deviates from the efficient area,the second baffle separation will be highlighted.The sand and gravel in the slug trap accumulates into a sand bed with a certain inclination.As the liquid level increases,the dip increases.The relationship between the volume of sand and baffle parameters,as well as the relationship between separation efficiency and the baffle parameters are esTablelished by the differential optimization method.Based on the continuity equation,the estimated time of the sand is deduced,which can provide guidance for the timely operation of the container equipment and other similar containers.