Experimental Study On Influences Of Inlet Duct Structures On Erosion Of Duct And Separation Performance Of Cyclone Separators

As a highly-efficient clean combustion technology, the circulating fluidized bed (CFB) boiler is used more and more widely in the field of power plant. The cyclone separator is one of the key equipments of CFB boilers to ensure the normal operation. The good performances of the cyclone can guarantee the high combustion efficiency and utilization of desulfurization in the boiler. However, many problems have been exposed in the actual operation, especially the low separation efficiency and erosion of surface wall, which severely restrict the application and development of cyclones. Now the CFB boiler is developing with large-scale and high parameters, which requires the arrangement of cyclones more reasonably.A visual cold circulating fluidized bed experimental setup based on a commercial135MW CFB boiler with a scale of1:10was built. Two kinds of inlet duct structures (angular-transition structure and smooth-transition structure) and three kinds of entrance inclination angles (15°,30°,45°) were designed.First, the influences of inlet duct structures on the collision frequency of solid particles on the wall of inlet duct and entrance target area were investigated. Results show that the collision frequency distribution of particles on the wall of inlet duct and entrance target area is uneven. For cyclone with angular-transition inlet duct, the collision mainly concentrates on the lower region of the left windward angular-transition surface and the lower region of the end of right target area. For cyclone with smooth-transition inlet duct, the collision mainly concentrates on the lower region of the left windward smooth-transition surface and the central and lower region of the end of right target area. The collision frequency of particles on the wall of angular-transition inlet duct is less than the collision frequency of particles on the wall of smooth-transition inlet duct significantly.Second, the influences of inlet duct structures and entrance inclination angles on the separation efficiency of cyclones were investigated. Results show that the separation efficiency of a cyclone with an angular-transition inlet duct is higher than the one with a smooth-transition inlet duct. Namely, the separation efficiency decreases firstly and then increases with the increasing of the entrance inclination angle.