Local Solids Holdup Research Articles

Hydrodynamics and local parameters in three-phase-flow in airlift-loop reactors of different scale

The reactor size and the solid phase have an important influence on the operation behaviour of airlift-loop reactors. Liquid velocity, dispersion, local gas holdup, and local solid holdup along the reactor axis have been measured in airlift-loop reactors with outer loop and a volume of 80L and 800L respectively. The measurements were done in two-phase-systems (air,water) and three- phase-systems (air,water,solid). To investigate the influence of the solid phase, different solid materials and different solid loadings were used. The liquid velocity and the dispersion were compared with results gained from a 2L outer loop reactor and a 70L inner loop reactor.

Wake solids holdup characteristics behind a single bubble in a three-dimensional liquid-solid fluidized

A light transmittance technique using a dual optical fiber probe was used to measure the local solids holdup in a three-dimensional gas-liquid-solid fluidized bed. The bubble can be clearly identified in the same signal, thus permitting the simultaneous determination of the local solids holdup profile in the wake of a single bubble and the rise velocity and chord length of the bubble. The solid holdup behavior was studied in the wake of single bubbles rising in a liquid-solid fluidized bed for different liquid velocities, particle sizes and bubble sizes. Over the range investigated in this study, the wake solids holdup was found to decrease with decreasing mean solids holdup in the bed, to depend only slightly on bubble Reynolds number and to decrease with increasing particle size.

Near-wake structure of a single gas bubble in a two-dimensional liquid-solid fluidized bed: solids holdup

Experiments were conducted to study the solids holdup in the near wake behind a single bubble in a two-dimensional liquid-solid fluidized bed. An optical fiber probe system was developed for the measurement of local solids holdup. Based on the local solids holdup distribution in the bubble wake, the primary-wake region was defined and its internal structure characterized. The studies indicate that, over a wide range of experimental conditions (particle diameter: 0.46–1.0 mm; particle density: 1.25–2.5 g/cm 3; bubble breadth: 1.55–4.79 cm; and superficial liquid velocity: 1.2–2.9 cm/s), the average solids holdup in the primary-wake region is virtually constant and independent of the bubble Reynolds number.