Measurement of particle velocity in fluidized beds is always technically difficult. A new method based on cross-correlation principle was proposed to calculate time-averaged velocity of particles. Considering the different reliabilities of signal segments, a cross-correlation coefficient was introduced into the formula for calculating time-averaged velocity. A PV6D optical fiber probe was used to obtain original signals in a fluidized bed with 200 mm i.d., and the time-averaged velocities calculated from three different methods were compared. The calculated particle volume flow rates based on different velocity calculating methods indicate that the method proposed in this paper is more reliable. Based on this method, particle time-averaged velocity was measured at different heights in the transition section of a turbulent fluidized bed. A modified three-zone drag law model was used to predict the flow structure of particles with clustering behavior. The experimental and simulation results both indicate that, from the transition section to the dilute section, particle velocity of the core region rises at first and then declines, the radial velocity distribution changes from a steep curve to a flat one, and then becomes steep again. This result depends on both solid concentration distribution and gas velocity distribution.
|Number of pages||9|
|Journal||Gao Xiao Hua Xue Gong Cheng Xue Bao/Journal of Chemical Engineering of Chinese Universities|
|State||Published - 1 Feb 2015|
- Computational fluid dynamics (CFD)
- Fluidized bed
- Optical fiber probe
- Particle velocity