Solid concentration and particle velocity distributions in the transition section of a ? 200mm turbulent fluidized bed (TFB) and a ? 200mm annulus turbulent fluidized bed (A-TFB)with a ? 50mm central standpipewere measured using a PV6D optical probe. It is concluded that in turbulent regime

the axial distribution of solid concentration in A-TFB was similar to that in TFB

but the former had a shorter transition section. The axial solid concentration distribution

probability density

and power spectral distributions revealed that the standpipe hindered the turbulence of gas-solid two-phase flowat a lowsuperficial gas velocity. Consequently

the bottomflow of A-TFB approached the bubbling fluidization pattern. By contrast

the standpipe facilitated the turbulence at a high superficial gas velocity

thus making the bottom flow of A-TFB approach the fast fluidization pattern. Both the particle velocity and solid concentration distribution presented a unimodal distribution in A-TFB and TFB. However

the standpipe at a high gas velocity and in the transition or dilute phase section significantly affected the radial distribution of flow parameters

presenting a bimodal distribution with particle concentration higher near the internal and external walls and in downward flow. Conversely

particle concentration in the middle annulus area was lower

and particles flowed upward. This result indicated that the standpipe destroyed the coreannular structure of TFB in the transition and dilute phase sections at a high gas velocity and also improved the particle distribution of TFB. In conclusion

the standpipe improved the fluidization quality and flow homogeneity at high gas velocity and in the transition or dilute phase section

but caused opposite phenomena at low gas velocity and in the dense-phase section.