A system for measuring bubble voidage and frequency around tubes immersed in a fluidized bed of particles.
Gas-solid fluidized beds are common in chemical processing and energy production industries. These types of reactors frequently have banks of tubes immersed within the bed to provide heating or cooling, and it is important that the fluid dynamics within these bundles is efficient and uniform. This paper presents a simple, low-cost method for quantitatively analyzing the behavior of gas bubbles within banks of tubes in a fluidized bed cold flow model. Two probes, one containing an infrared emitter and one containing an infrared (IR) detector, are placed into adjacent glass tubes such that the emitter and detector face each other. As bubbles pass through the IR beam, the detector signal increases due to less solid material blocking the path between the emitter and detector. By calibrating the signal response to known voidage of the material, one can measure the bubble voidage at various locations within the tube bundle. The rate and size of bubbles passing through the beam can also be determined by high frequency data collection and subsequent analysis. This technique allows one to develop a map of bubble voidage within a fluidized bed, which can be useful for model validation and system optimization.
PTV profiling of particles motion from the top and side of a swirling fluidized bed
A swirling fluidized bed (SFB) operation heavily depends on geometry of the solid particles and gas distributor. This study was aimed at investigating the hydrodynamics of the solid particles in a SFB, set into fluidization using an annular blade distributor. MATLAB supported particle tracking velocimetry (PTV) was engaged to generate the velocity vector profiles of the top surface and side of the swirling bed. The pressure drop curve suggested that the uniform bed swirling happens at the superficial air velocities between 2 m/s and 2.6 m/s. The average particle velocity, both at the top and side of the bed, exhibited a monotonically increasing trend over the superficial air velocity. However, an inverse relationship was predicted between particle velocity and the bed height. At lower superficial air velocities, a Gaussian distribution of the velocity vectors was predicted along the radius of the bed. Particles in the vicinity of the bed walls moved relatively slower than those marching in the middle of the bed. However, the average particle velocity was decreased with an increase in the blade fin angle and inclination angle. Overall, the particle velocity at the top surface of the bed remained slightly lower than along the side of the bed.
The Story of Troilus
Originally published by J.M. Dent and Sons Ltd., 1934. In this volume Gordon presents the four great medieval versions of the love of Troilus and Criseida: Benoit de Sainte-Maure's Roman de Troie, written in approximately 1160 and the earliest surviving version of the story; Giovanni Boccaccio's It Filostrato (c 1338), which drew on Benoit's tale for one of its two main sources; Georffrey Chaucer's Troilus and Criseyde c 1385), for centuries considered his best work; and Robert Henryson's Testament of Cresseid (c 1490), which functions as a continuation of the story Chaucer tells.