Numerical Simulation And Experimental Research Of Two-stage Gas Liquid Cylindrical Cyclone

In order to adapt to the rise of high-efficiency separation equipment,according to the working environment of onshore and underwater gas-liquid separation,the first generation of two-stage gas liquid cylindrical cyclone has been improved and the design of two-stage gas liquid cylindrical cyclone A and B which are for onshore and underwater separately have been proposed.The device is based on a conventional cyclone gas-liquid separator,which provides a separation place for the gas-liquid two phases by extending the gas riser,and then fully utilizes the residual kinetic energy of the primary swirling flow to form a secondary swirl flow in the gas riser,to improve the separation efficiency.Guided by the theory of gas-liquid two-phase flow in multiphase flow,by the combination of numerical simulation and experimental research,the flow field characteristics and separation characteristics of two-stage gas liquid cylindrical cyclone A and B are explored,especially the working characteristics of the device under special conditions with low gasliquid ratio.This research has reference significance for the design and manufacture of domestic efficient separation equipment.The main research contents and conclusions are as follows:After the investigation of different types of gas-liquid separation equipment from all over the world,seven improvements have been made to the first-generation two-stage gas liquid cylindrical cyclone,which made the production cost more economical and more suitable for modern gas-liquid separation and gathering requirements.At the same time,the design scheme of the underwater separation device is added,and the built-in liquid discharge pipe allows both the gas and liquid phases to be discharged from the top of the device after the separation,thereby greatly saving the construction amount of the underwater seabed excavation.Starting from the root cause of the separation efficiency deterioration of the two-stage gas liquid cylindrical cyclone,the fracture characteristics of the liquid droplets in the gas cyclone field are taken as the entry point,revealing that the droplets escape directly from the tangential inlet into the device and then escape through the gas phase outlet is the root cause of the deterioration of device performance,rather than the droplets being shredded by the swirling flow inside the device and then broken.Based on the above theory,the coordinate system of the Navier-Stocks equation is transformed according to the regular structural shape of the device,and the pressure distribution of the internal gas phase swirl field of the device is mathematically modeled,and the reference standard of the device cylinder diameter design is summarized.After the model is established,the applicability is verified by experiments,and the model calculation results are in good agreement with the experimental results.Taking the stripping of the main separation zone as a simplification method,ANSYS ICEM is used to carry out more regular fluid domain meshing,and numerical iterative calculation by ANSYS Fluent is carried out to calculate the variation law of the internal gas phase flow field under different inlet structures and device types.The results show that the increase of the tangential inlet necking ratio(ie,the increase of the tangential inlet cross-sectional area)has a steady flow effect on the gas phase flow field inside the device.When the inlet necking ratio is 0.7 or more,the internal flow field of the device is the most stable.The built-in drainpipe of the device increases the wall friction effect caused by the outer wall surface,so the velocity of the B-type device with the built-in drainpipe is smaller than that of other structures in each cross section.Just the same with that the ratio of the built-in drain pipe to the inlet necking is too small,the kinetic energy at the inlet of the device cannot be smoothly transmitted to the bottom,so the reverse migration of the gas phase space occurs at the bottom of the device.The experimental study was carried out to study the working characteristics of the two-stage gas liquid cylindrical cyclone under special conditions in low gas-liquid ratio,and the pressure drop variation characteristics and inlet flow pattern were analyzed.According to the experimental phenomena and experimental data,the inlet flow patterns of 2 major categories or 7 sub-categories are summarized,and the development of the flow pattern is analyzed in combination with the captured pressure drop signal.The concept of the overall pressure drop of the device is proposed,and the waveform analysis,discrete analysis and quantitative analysis are carried out.The analysis results are summarized and the pressure drop signal is applied to the columnar two-stage gas liquid cylindrical cyclone under special conditions with low gas-liquid ratio to judge the criteria for the judgment of the entrance flow pattern.This work provides guidance for the development of automatic control system of this kind of device,and provides a reference for the safe operation of the device and the accident prediction.