The Simulation Researches On The Two-Phases Flow Of Preheater Cyclones

Preheater Cyclone is one of the most crucial equipments in the production of New Dry-Process cement production, its resistance and separation efficiency should be taken into account in the design and product processes. Due to the slow theoretical and experimental research progress, the design and reconstruction of cyclones are still carried out under practical experiences at present. In this dissertation, computational fluid dynamics (CFD) was applied in the numerical simulation of Two-Phase flow in the preheater cyclone, and the Two-Phase flow field in the preheater cyclone was simulated using Fluent.The work in this dissertation is mainly for the following:(1) The most suitable method for the numerical simulation of preheater cyclone was found, including the division of computational domain mesh, the choice of theoretical modeling, the choice of numerical calculation method, etc.(2) The gas flow field in the preheater cyclone was studied; the three-dimensional velocity distribution, pressure distribution and the flow characteristics of turbulent structure were analyzed.(3) The three-dimensional Two-Phase flow in the preheater cyclone was studied, the particle trajectories, the influence of different structure parameters and operating parameters to the pressure and separation performance of the preheater were also analyzed.Based on the simulation results by some of the main conclusions are as follows:(1) A set of numerical calculation method was established for the simulation of the complex flow field in the preheater cyclone: high quality mesh was needed when simulating the complex flow field in the preheater cyclone; second-order difference and PRESTO pressure interpolation should be applied with the anisotropy turbulence model (RSM) to obtain a better prediction results.(2) The numerical calculation algorithm used in this dissertation was simple; the movement of the particles can be better tracked when they had complex experience, and the trajectories of the particles of different sizes and different positions can be forecasted.(3) The particles with small sizes had complex trajectories and can be greatly influenced by turbulent flow. The locations of the small particles vary even with the same size and incident position. Besides, the small particles are more likely to be influenced by the second eddy current.(4) The size of the particles and the velocity of the import flow had remarkable influence on the separation efficiency of the cyclones.(5) The insertion depth of the exhaust pipe was a contradictory factor for the preheater cyclones and separation efficiency.