Numerical Simulation And Parameter Optimization Of Gas-liquid Two-phase Separation In Arc-shaped Branch Pipes

As the demand for oil and gas resources increases,the ocean will also become the focus of oil and gas development.For the current shallow ocean gas hydrate mining in China,through the underwater production system of the seabed surface,the obtained natural gas hydrate slurry can be separated underwater on the seabed,which can reduce the energy consumption and reduce the use of hydrate inhibitors.Existing subsea multiphase flow separators are not only bulky,but also costly to manufacture,install and operate.Due to the simple structure,small size,high pressure bearing capacity,easy processing into standard parts,low manufacturing and installation and installation cost,high operational reliability,such tubular separation will be an important development direction of multi-phase separation of the seabed.Therefore,based on the T-tube structure,a curved branch pipe structure is proposed,and the separation mechanism and effect of the arc-shaped branch pipe and the T-shaped branch pipe are compared,and a comparative study is carried out.At the same time,the influencing factors,application scope and parameter optimization of the separation efficiency of the arc-shaped branch pipe are studied in depth.Specifically,this paper mainly carried out the following research work:(1)Through the investigation of domestic and foreign literatures,the research status and progress of gas-liquid separation of T-tubes are known.(2)Development and verification of numerical model for gas-liquid two-phase flow.According to the basic theory of gas-liquid two-phase flow and computational fluid mechanics,the mechanical behavior of gas-liquid two-phase flow in the pipeline was analyzed.The numerical model of gas-liquid two-phase flow simulation in the tube was developed and verified by experiments.(3)The operating parameters of the curved branch pipe are preferred.Using the developed and verified numerical model,the simulation simulates the flow law of gas-liquid two-phase in the curved branch pipe.Through the orthogonal experimental design method,the orthogonal test scheme of 4 factors and 5 levels affecting the gas-liquid two-phase separation efficiency of the curved branch pipe was determined,and the optimal inlet parameter combination was obtained by orthogonal experiment optimization.At the same time,the influence of flow pattern and split ratio on separation efficiency was analyzed.(4)The curved branch pipe structure parameters are preferred.Under the optimal combination of parameters,the influence of branch pipe position angle,branch pipe inclination angle,arc tube radius of curvature and pipe diameter ratio on separation efficiency was analyzed.The separation mechanism of gas-liquid two-phase in curved branch pipe was analyzed.Through the above research,the flow law of gas-liquid two-phase in the arc tube was mastered,and the optimal operation parameters were matched by orthogonal experiment optimization,so that the separation efficiency of the curved branch tube reached 93.59%.The factors affecting the separation efficiency of the curved branch pipe were found to be the split ratio,the gas phase inlet velocity,the liquid phase inlet velocity and the gas volume fraction.It was found that the inlet flow pattern most suitable for the separation of the curved branch pipe was a plug flow.Based on the optimal inlet operation parameters,the parameter parameters of the curved branch pipe are optimized.The research results in this paper provide a valuable reference for the separation design of gas-liquid two-phase tube.