Numerical Analysis And Optimization Design Of Gas-Liquid Cylindrical Cyclone Separator In Deepwater

In the development of deepwater oil and gas fields,underwater separators are of great significance in reducing back pressures of wellheads,reducing dosages of chemical reagents such as ethylene glycol,eliminating slug flows and finally enhancing oil and gas recovery.Conventional gravity-based separators are limited in their applications in deepwater conditions due to their large sizes and low separation efficiency.In contrast,GLCCs stand out from numerous separators and earn a wide range of applications,benefiting from their compact size,simple structure and high separation efficiency advantages.However,the gas-liquid two-phase flow within the GLCC is very complex and still lacks an effective process design method.Therefore,this paper utilizes numerical simulation technology to analyze GLCC internal flow field and optimize its structure,and conclusions are shown as following:(1)Three kinds of turbulence models of GLCC numerical simulation are studied,including Mixture RNG k-?,Euler RNG k-? and RSM.It is found that three models can form asymmetric zero-axis rotation in the center of the cylinder and stratified laminar flow in inclining inlet pipe.Compared with indoor experiment and field test,the RSM turbulent model is the most accurate and can provide guidance for GLCC numerical simulation in the future.(2)It is found that the non-axisymmetry of GLCC single inlet structure causes the contraction effect of inlet runner and the swing instability of flow field in main cylinder separation space,so that the center of rotation of flow field deviates from the geometric center of GLCC.In a certain range,the instability degree of rotating flow field increases with the inclining inlet pipe lengths and decreases with the inlet nozzles areas.(3)The RSM model is utilized to simulate internal flow filed of GLCC with different lengths of inclining inlet pipes and different areas of inlet nozzle.The optimization structure and the corresponding design curve of GLCC inclining inlet pipes are obtained by setting the separation efficiency and the separation pressure drop as optimization targets,which can be used for the GLCC process design.(4)The sensitivities of GLCC material parameters,structural parameters and working parameters are studied by stochastic finite element method based on ANSYS-PDS module.The reliability of GLCC is 99.7871% and 99.9316% respectively calculated by Monte Carlo method and Response Surface method.According to the stress-intensity interference theory,the limit state function is modelled.The material yield limit,Young's modulus and internal pressure load are more sensitive to the limit state function than other relative parameters,which breaks the traditional reliability calculation based on the determined parameters and is of great significance to the safe operation of GLCC.