Study Of Revamping Of Cyclone Separation Unit In Circulating Fluidized Bed Boiler

In the cyclone separator with downward exhaust gas, depending on the centrifugal force generated by rotation movement of gas-solid phase fluid, the solid particles are separated from the air phase. With the advantages of simple structure, easy maintenance, low pressure loss, easy to decorate and branch, it is widely applied in the flue gas desulfurization technology with circulating fluidized bed boiler and circulating fluidized bed. Because of the strong three-dimensional rotating turbulence of gas-solid phase in the cyclone separator, accompanied by two separate movement, and many complicated physical phenomena such as condensation, adsorption, and electrostatic interaction, it makes the theoretical research great difficult. The traditional design relies on the experience to select the structure of cyclone separator and size,and the design process has a great deal of blindness.In this paper, a UG-35/3.82-M35circulating fluidized bed coal boiler in operation is studied, which has a low separation efficiency, heavy fly ash and larger thermal loss. The cyclone separator is reconstructed. The Computational Fluid Dynamics commercial software FLUENT is used to study the cyclone separator with downward exhaust pipe with and without modification. Based on the modification, the appropriate numerical simulation method is chosen. The data of gas phase velocity field, pressure field, particle trajectory and particle sizing efficiency, total separation efficiency of the cyclone separator can be obtained by the numerical simulation. According to the simulation results, the appropriate retrofit scheme is presented. Through the practical application in engineering, it is found that the simulation results agree well with those obtained in the experiment. It is also verified that the CFD numerical simulation is available in the modification of exhaust cyclone separator.