Investigation On The Integrated Optimization Of Combined Gas-liquid Separator

For a long time,there exists problems in horizontal three-phase separator of oil field,like disorder in flow field,serious oil-water emulsion,cutout of flow or overflow when slug flow pound.These shortcomings restrict the separation efficiency seriously.In this paper,a kind of combined gas-liquid separation system is studied based on branch tee line combined with gravity separator.Based on Zhang-Sarica general hydraulic and slug dissipation model,a calculation method for characteristic parameters of slug flow is established before and after the flow pattern transition,and it is compared with the test datas of relevant researchers.The results show that the various characteristic parameters and the slug dissipation distance are good agreement with the test results,only the liquid film and liquid slug holdup local exist some errors locally,but it is still within the scope of the project.Experiments have studied the discipline of slug dissipation and evolution along the declination pipe.The dissipation process can be summarized as follows: under the effect of gravity(or pressure),liquid in the wedge head(tail)of slug continuously falls off along the gas-liquid interface of wedge shape from the top of the pipe and enters into the front(back)liquid film zone.With the process of the liquid slug dissipation,liquid film zone flow out the downward inclined pipe acceleratedly,with the length increasing gradually,The gas-liquid interface gradually becoming smooth and neat.Finally the head of slug meets with the tail,forming a critical point of liquid slug dissipation—“point of cusp”.During the slug dissipative process in the declination pipe,the slug does variable acceleration movement,and the slug acceleration is different during d ifferent dissipation distance.Tail speed of the slug is greater than the head speed.slug velocity is between the head and tail velocity of the liquid slug.Slug dissipation rates present significantly positive correlation with the difference of the head or tail slug velocity and the slug bulk velocity.When the gas superficial velocity is low,the slug bulk velocity grows exponentially,and the dissipative characteristics can be described as "head of the slug losses and the tail is stable ".On the other hand,the slug bulk velocity is in the elliptic growth,and dissipation characteristics are shown as "stable head,tail off".The increase of inclined pipe's angle makes the liquid slug head,tail wedge gas-liquid interface gradually become neat and smooth,and it is advantageous to the liquid slug,and the best angle is between-27 ~-30 °.Under the same conditions,when the liquid slug which is proportional to the initial liquid slug length flows out by dissipative structure of downward inclined pipe,the ratio of residual liquid slug length increases with the increase of the ratio of initial liquid slug length,and it's amplitude of deviation to diagonal becomes more and more obvious.This suggests that for large liquid slug length,adopting the way of setting liquid slug inlet splitting device is superior to increase the volume of slug catcher.By means of Fluent software simulator,according to the simulation of inlet component,rectifying plate and mist component structure in the gravity separato r,accordingly,key design parameters are optimized,and the complete combined separation system design method is formed.