Structure Optimization Study Of Axial Flow Gas-liquid Cyclone Separator

In recent years,with the continuous development of offshore oil and gas fields,the content of free water and condensate in produced gas has gradually increased.Under the background of limited offshore platform space,in order to meet the requirements of gas-liquid separation,vigorous development of compact gas-liquid separators has become a new trend.Based on theoretical analysis and numerical simulation,a structure scheme of an axial-flow gas-liquid cyclone separator is proposed in this paper.On this basis,an experimental prototype of the separator is manufactured.The separation performance of the experimental prototype is studied through experiments.The separation efficiency model and pressure drop model are established.The main conclusions and research contents are as follows:For mist inflow,based on the study of gas-liquid two-phase flow in the separator,the force and movement of droplets in the swirling flow field are analyzed.The conceptual design of the components of the separator is carried out according to the mechanism of the separator structure on the fluid.The geometric model of the axial-flow gas-liquid cyclone separator is established,and the key size parameters of the separator are defined.Combining with cyclone separation mechanism,RSM turbulence model and discrete phase model were used to simulate gas-liquid two-phase flow,and the effect of separator structure parameters on separation performance was analyzed.The results show that the internal flow field can be improved by setting the center body inside the separator,and especially can enhance the separation of small droplets.Increasing the center diameter Di,increasing the number of diversion vanes and decreasing the outlet angle?of diversion vanes can increase the tangential velocity of the gas and improve the separation efficiency,but it will also increase the pressure drop of the separator.The influence of exhaust pipe diameter De on separation efficiency is relatively low.In order to reduce the pressure drop of the separator,the exhaust pipe diameter De should not be too small.The simulation results show that the separation efficiency of the separator tends to be stable with the increase of the separation zone length,but has little effect on the pressure drop.According to the above rules,the structure parameters of the separator are selected and the experimental prototype is produced.The influence of separator structure parameters and operation parameters on separation performance was studied by experiments.Under the experimental conditions,when the gas velocity is less than 7m/s,reducing the outlet angle of guide vane?and increasing the diameter of centroid Di can increase the separating efficiency of separator.There is a certain critical gas velocity which can make the separating efficiency of the separator with a specific structure reach the maximum,and the separating efficiency decreases gradually with the increase of gas velocity.At a certain gas velocity,the separator efficiency increases with the increase of inlet liquid content,when the gas velocity is high,the separator efficiency decreases.Experiments show that the critical gas velocity which makes the separator achieve the highest separation efficiency has nothing to do with the inlet liquid concentration and is mainly affected by the separator structure.Based on the experimental results,the phenomenon of liquid entrainment in the axial-flow gas-liquid cyclone separator was analyzed,and three kinds of entrainment mechanisms were summarized:entrainment in the separation zone,entrainment in the collecting chamber and entrainment in the exhaust pipe peristalsis.By analyzing the interaction between gas and liquid film,the criteria for determining the initial liquid entrainment of separation zone and collecting chamber are established,and a skirt edge is designed at the entrance of exhaust pipe to prevent the peristaltic liquid film from escaping along the wall of exhaust pipe.For the entrance flow with a certain droplet distribution,the theoretical model of particle separation efficiency and overall separation efficiency of the separator is established by analyzing the movement law of the droplet in the internal flow field of the separator,and the critical droplet size d_p,c which can be completely separated is determined.According to the pressure drop composition of each part,the overall pressure drop model of the separator is established and verified by experiments.On the basis of geometric similarity of separator structure parameters and dimensionless treatment of other influencing parameters,a scale relation criterion between separator separation efficiency and pressure drop is established.