CFD SIMULATION OF CYCLONE SEPARATOR USED FOR CIRCULATING FLUIDIZED BED BOILER

Abstract

ABSTRACT: A cyclone separator plays a critical role in separating solid particles from fluids in a circulating fluidized bed boiler. The problem of exhaust pipe deformation occurs during the application of the cyclone separator in power plants. This deformation has a direct relationship with the flow field distribution in cyclone separators. In this paper, the flow field is explored to improve the operation and efficiency of the cyclone separator by means of computational fluid dynamic techniques. The Reynolds stress model provided by FLUENT software is applied to study flow dynamics of a full-size cyclone separator used for a circulating fluidized bed. The effect of the insert depth of the exhaust pipe on the flow field and performance of cyclone separator is investigated computationally. Results demonstrate that the pressure drop of the cyclone separator obtained from the numerical simulation agrees well with the pressure drop measured in an experiment in a power plant. The exhaust pipe depth has an insignificant effect on the pressure drop and velocity distribution. The pressure drop initially increases with the inset depth of the exhaust pipe and then decreases with the insert depth of exhaust pipe. The exhaust pipe exerts a large pressure when the exhaust pipe length is too short or too large. Increasing the insert depth of exhaust pipe can reduce the number of particles that escape from the cyclone and improve separation efficiency. Investigation results of full-size cyclone separator are significant in understanding the behavior of the large cyclone separator for circulating fluidized bed boilers in power plants.