Structural Optimization And Numerical Simulation Of Gas-liquid Cylindrical Cyclone

During natural gas extraction and transportation,it is essential to separate and process the natural gas mixture to ensure extraction efficiency and transportation safety.The Gas-liquid Cylindrical Cyclone is widely used in the petrochemical industry due to its simple structure,high separation efficiency,small footprint,and good pressure-bearing capacity.It plays a crucial role in deep-sea oil and gas field development.To enhance separation efficiency and reduce liquid escape from the overflow port,this study optimized the downward pipeline structure based on the traditional Gas-liquid Cylindrical Cyclone and proposed a three-inlet Gas-liquid Cylindrical CycloneFirstly,to demonstrate the separation performance of the three-inlet Gas-liquid Cylindrical Cyclone,the Euler multiphase flow model and Euler wall film model were used to numerically simulate the velocity,pressure,gas-liquid ratio,and liquid film distribution inside the vortex field.The optimized structure of the downward sloping pipeline,which diverts the mixture when it enters,was found to have a significant role in improving separation efficiency.After entering the vertical cylindrical body,the liquid phase is influenced by centrifugal force and gravity,and is collected at the bottom and discharged from the bottom outlet.Meanwhile,the gas phase is forced to swirl in the center and is collected in the upper cylindrical body and discharged from the overflow port.Secondly,the impact of operating parameters on separation performance was analyzed based on the same multiphase flow model.An increase in average inlet mixture velocity leads to a decrease in separation efficiency due to the high-speed gas flow carrying more liquid,which escapes from the overflow port.Increasing the liquid volume fraction also leads to a decrease in separation efficiency,but the impact is smaller compared to the impact of average inlet mixture velocity.The size of the liquid droplet diameter at the inlet also affects the separation efficiency,with smaller droplets more easily entrained by the gas flow.It was found that when the average inlet mixture velocity is controlled below 10m/s,the liquid volume fraction is controlled below30%,and the inlet liquid droplet diameter is controlled above 10μm,the gas-liquid separation efficiency can reach above 90%.Thirdly,the DPM model was used to explore the aggregation and fragmentation of liquid droplets in the vortex field at the microscopic level.The double R distribution was used to control the inlet liquid droplet diameter between 5～20μm.The simulation showed that at an inlet mixture velocity below 20m/s,the liquid droplets tend to aggregate into larger droplets in the main downward sloping pipeline.After entering the vertical cylindrical body,liquid droplets with a diameter of about 5μm are more easily entrained and escape from the upper overflow port due to the influence of the central vortex,while larger liquid droplets are more easily trapped and form a liquid film by colliding with the wall.With an increase in the average inlet mixture velocity,the number of droplet aggregation decreases,and the Sauter mean droplet diameter decreases,which affects the diameter of the escaping droplets captured in the overflow port pipe.Finally,the influence of different structural parameters of the three-inlet Gas-liquid Cylindrical Cyclone on separation performance was investigated.The Euler multiphase flow model and Euler wall film model were used to numerically simulate the effect of the angle and spacing between the main downward sloping pipeline and the pre-separated gas pipeline on separation efficiency under different average inlet mixture velocities.It was found that when the angle is 117° and the spacing is 400 mm,this structure of the three-inlet Gas-liquid Cylindrical Cyclone can maintain a separation efficiency of over 90% when the average inlet mixture velocity is below 20m/s.Compared with the traditional Gas-liquid Cylindrical Cyclone,the improved structure of the Gas-liquid Cylindrical Cyclone can achieve a more significant separation effect,greatly reducing the phenomenon of liquid escaping from the upper overflow port,thereby improving separation purity and efficiency.This study provides a structure optimization idea for Gas-liquid Cylindrical Cyclone and provides a reference for subsequent numerical simulation of the same type of gas-liquid cyclone.