A Numerical Simulation In The Preheating Cyclone

Two-phases flow in a preheating cyclone with pentagonal inlet and three core volute structure was simulated by CFD software in this paper. Against feature of nonaxisymmetrical structure and three-dimension strongly swirling flow field of the preheating cyclone, computation zone was discrete by non-structur tetrahedron grid in the model building. Reynolds Stress Model was used to simulate turbulence flow, meanwhile, Stochastic Trajectory Model was adopted to track the trajectory of particles.Through comparison experimental with simulation result, the reliability of numerical method was validated. Based then, solid model was built with industrial scale equipment directly in order to obtain more creditable simulation result. From simulation results, main performance of the preheating cyclone under different operation parametes and structure parameters was compared and given optimum suggests.The results of simulation indicate that the flow field of preheating cyclone with pentagonal inlet and three core volute structure presents obvious nonaxisymmetrical structure. This result in the deviation of centerline of pressure field and velocity field from axial line of preheating cyclone, and the centerline is screw swinging distribution. And comparing with cyclone in other domain, the preheating cyclone with pentagonal inlet and three core volute structure reduce the effects of fluid collision and compress each other significantly near the inlet. The performance of the preheating cyclone can improve compare with common cyclone which used in other domain.By analyzing simulation results under different operation parameters and structure parameters, conclusions can be draw as follows: (1)As inlet velocity increase, the static pressure near axial line will reduce gradually from bottom to the inlet of inner tube of cyclone;(2) When the length of inner tube reaches a value, the pressure field will keep stable relatively. But the pressure gradient of annular chamber near the inlet of inner tube will increase as the length raise, this give the reason that the local pressure drop willincrease with the length of inner tube. (3)When the particle diameter is greater than 100 urn, the force actived on the particle reaches the state of dynamical balance, then the particle retention time will prolong. ? The raise of the length of inner tube can improve collection efficiency for greater partical size obviously, but it affects fine particle scarcely. The conglobation of fine particle explain this phenomenon. ?As inclination angle of cone reduce, collection efficiency will improved.