Radial Particle Profiles in a Liquid‐Solid CFB with Varying Viscosity

Abstract

Flow structure was characterized in a 76 mm diameter by 2.0 m high liquid-solid circulating fluidized bed (LSCFB) with different viscous liquids ranging from 1.0 mPa´s to 4.8 mPa´s. Measurements of mean and local solids holdup were carried out in the axial and the radial direction, respectively. The results showed that a uniform axial and a nonuniform radial distribution of the time-averaged solids holdup appeared in the LSCFB. The viscosity of the liquid phase reduces the nonuniform distribution of solid particles in the radial direction. By examining the instantaneous data signals, flow behavior in a viscous system was found to be more uniform and less vigorous. To further understand the hydrodynamics in a LSCFB, Hurst's rescaled range (R/S) analysis was also adopted to analyze its stochastic characteristics and the local flow properties.

Hydrodynamics of a liquid–solid circulating fluidized bed: Effect of dynamic leak

“…In this arrangement, the solids feed pipe connecting the riser and downcomer makes an angle with the axis of the riser and the axis of the downcomer. In the second arrangement, the main liquid is sent through a porous plate distributor at the bottom of the riser and the other stream is sent through an L-Type valve connecting the riser and the downcomer [6,[19][20][21][22].…”

Solid holdup in liquid solid circulating fluidized bed with viscous liquid medium

“…The effect of liquid viscosity on the solid inventory with riser operated in a fixed inventory mode was done by Vidhyasagar et al [18]. The effect of liquid viscosity on the riser operated in variable inventory mode was studied by a few investigators with respect to solid behavior and flow structure [19,20,23]. There were few reports [19][20][21] available on the effect of viscosity on mixing, heat transfer, regime transition and radial solids distribution in the case of variable inventory mode of LSCFB.…”

Numerical Investigation of Phase Distribution and Liquid Turbulence Modulation in Dilute Particle-Laden Flow

“…Kaftori et al (1995aKaftori et al ( , 1995b experimentally concluded that the particle motion is controlled by wall coherent structures. Some literature (Liang et al 1996;Zhu et al 2000;Zheng 2004) reported that the radial profile of particles is associated with liquid velocity, particle density, liquid viscosity and particle circulation rate, and the radial nonuniformity increases with the increase of liquid velocity and particle circulation rate. Suzuki et al (2000) discovered that particles are densely distributed along the low-speed streaks.…”

“…With the development of fluidization techniques, the solid-liquid flows exhibit more and more merits in industrial applications, such as improved interphase contact efficiency, ease in handling large quantity of particles, and uniform temperature distribution, etc. (Liang et al 1996;Zhu et al 2000;Zheng 2004;Limtrakula et al 2005;Hashizume and Morita 2008). These characteristics have led to the fact that solid-liquid fluidized beds rapidly gain popularity in many industrial processes, such as synthesis of chemicals, petroleum refining, hydrometallurgy, food technology, biochemical processing, water treatment, etc.…”