Numerical Simulation Of Velocity Multi - Rotating Cyclone Separator

The cyclone separator is an important equipment in the process of natural gas purification. It can separate the dust from natural gas via the centrifugal force created by rotating airflow. At present, the axial inlet vane-type multi-tube separator is widely used in most gas stations, because the vane-type structure has a simple structure, high separation efficiency and large gas storage capacity compared to the tangential entry type. With the improvement of the energy saving requirement, a better performance of cyclone separator is required, which demand not only much more higher separation efficiency, but also much lower pressure drop. In this paper, we take the modern multiphase flow theory, advanced fluid mechanics and computational fluid dynamics as theoretical guidance while combine the numerical simulation with theoretical analysis to achieve some targets as follow: figuring out the main factor parameters on separation efficiency and pressure drop of cyclone separator; researching the internal gas-solid flow pattern and particle separation mechanism of vane-type cyclone separator; providing parameter guidance for the field application and theoretical guidance for the further optimistic design of cyclone separator.Firstly, based on the Navier-stokes and continuity equations, with the use of Reynolds stress model and the finite volume method the fluid flow is simulated including velocity and pressure field of a single cyclone tube and understand the gas-phase flow pattern inside the single tube. Besides, for the application of discrete phase model, the separation efficiency of a single tube is gained by analyzing the movement pattern and the trajectories of particles with different sizes in the separator. Analysis shows that the cyclone fluid field is composed with the downward rotational flow in outer space and the upward forced vortex in middle space. Besides, there are also some other secondary flows, such as partial short-circuit and back mixing flow. When the particles get into the separator, they firstly move toward the wall by the guiding role of the vane. Secondly they move to the bottom surface by the rotational flow in outer space and then be collected by the dust mouth located at the bottom surface. This is the ideal situation. However, some particles can not reach the bottom surface. For example, some particles will reach the vicinity of the exhaust port and then escape from the exhaust port by the influence of short-circuit; and some particles that have moved to the bottom surface will move up to the exhaust port by the influence of back mixing flow, which is the main reason of lower separation efficiency.Secondly, the different air inflow of a single-tube cyclone separator has an effect on the pressure drop and separation efficiency. After analyzing it, we get a reasonable inlet velocity of gas and make sure the best air inflow in order to guide the engineering field. At the same time, we also research four different insertion depth of exhaust pipe to see how they affect the pressure drop and separation efficiency. Their depth are 125mm,150mm,175mm,200mm. Besides, four different vane angles are researched too. Finally, the fluid field and separation efficiency are analyzed under different vane height. Based on all of these studies, the structure of cyclone separator is optimized.Thirdly, the pressure drop and airflow distribution of inlet chamber, plenum chamber, and exhaust chamber were researched, and the particle sedimentation rule of multi-tube separator and the cross flow of gas in plenum chamber of single tube are analyzed by doing numerical analysis to multi-tube cyclone separator.Finally, numerical analysis to the multi-cyclone separator was done to research the pressure drop and airflow distribution in the inlet chamber, plenum chamber and exhaust chamber. The intake uniformity of gas among each tube, and the cross flow among them in the plenum chamber were also anglicized. After all analysis, the movement regular of particles in multi-cyclone separator was given and the separation efficiency of it was also simulated; online measurement technology was used to measure the separation efficiency of actual separator in real gas station, and compared to the simulated result,the result matches good.