(273b) The Comparison of Large Square Cyclone and Centrifugal Cyclone by Numerical Simulation

The separation efficiency, pressure drop and wear for large square cyclone and centrifugal cyclone with the same hydraulic diameter, were numerically compared. The numerical study was made by Barracuda, a commercial code, in which Eulerian–Lagrangian procedure was used. In order to evaluate the code, the calculated results have been compared with measurement data taken from the literature. The comparisons showed the numerical simulation was reasonable. The square and centrifugal cyclone, which were with the same vortex finder, the same area of inlet and the same velocity of gas and particle, have been numerical studied. By observing the numerical results of mass flux vector of particles, it was found that the mechanisms of separation of particles for square and centrifugal cyclone were different. Centrifugal cyclone separated the particles by centrifugal force, while the square cyclone separated the particles both by collision with wall and by centrifugal force. The large particles were primarily separated by wall collision, while small particles were primarily separated by centrifugal force. The numerical results showed that the square cyclone had lower separate efficiency than the centrifugal cyclone. The separation efficiencies for various diameters of particles have been studied. It was found that the separation efficiency of square cyclone is much lower than the centrifugal cyclone for small particles, while almost the same separation efficiency for large particles.  The numerical results showed that the square cyclone had lower pressure drop and lower wear than centrifugal cyclone. The effect of load at input was also investigated. It was found that the load did not affect the separation efficiency greatly, but the change of pressure drop is smaller for square cyclone than for centrifugal cyclone.