Numerical Simulation Research On The Two-phase Flow In A Diffusible Cyclone Separator

The two-phase flow in a diffusible cyclone separator is discussed with numerical simulation in this paper. The main research content consists of the basic flow pattern, separating efficiency, the effect of some geometrical sizes on the pressure loss and efficiency, the ways to reducing pressure drop, and the wall erosion condition because of solid particle impingement.To explore the flow pattern the RNG κ — ε (Renormalization group κ - ε) turbulent model is adopted. At the same time ,DPM(Discrate Phase Model)model is used to track particle trajectory. Results show that the flow pattern is two-layer structure and intensive shearing action exists between the two layers. The distribution of axial velocity, radial velocity (exception in the diffusible part) and tangential velocity takes on a good symmetry. Below the reflecting cone in cyclone the high static pressure and low velocity is its main characteristic. For separation of solid particle which diameter smaller than 4 μ m the cyclone is not suitable. Some shortcut flow near the inlet of vent-pipe still occurs. In this paper we have shown particle trajectories of 5 typical diameters. The relationship between inlet velocity and pressure drop , and the effect of reflecting cone on particle settling time before escape have been analyzed too.Some geometrical sizes' actions on the pressure loss and separate efficiency are investigated in detail. Basing on numerical simulation results we point out the relatively reasonable scopes of some sizes for optimization design(i.e.low pressure-loss and high separate- efficiency).Low pressure-loss is significant to save cost in operation. Three kinds of reducing pressure-loss ways are introduced to this paper, i.e. adding rpds (reducing pressure-drop stick) outside the vent-pipe, mounting center-body in the vent-pipe and fitting them together. For each kind we show the extent of reduction and the corresponding change of separate efficiency. The contours of velocity, turbulent kinetic energy and vorticity magnitude with rpds have been compared with that of without rpds. The maximal magnitude of pressure-loss reduction can get to 20 percent. It's better to adopt the square section rpds than a round section rpds if the rpds is mounted outside vent-pipe, and the best range of azimuth angle is 180° ～240° . Upwind width and position of the rpds work heavily on the extent of pressure-loss reduction and change of separate efficiency.Erosion damage is common in solid particle separator because of particle impingement and other reasons. The Finnie erosion model is utilized to simulate the wall erosion of diffusible cyclone separator. From the pictures we know that different part has different erosion level. In general the upright walls of helicoids shell, the upside surfaces...