(583gc) Effect Of Bed Size, Particles Properties and Gas Velocity On The Phases Distributions Of Gas-Solid Spouted Beds Using Gamma Ray Computed Tomography

Gas-solid spouted beds have found wide applications in various industrial processes such as coating, drying, granulation, combustion, gasification, reaction, etc. Recently with the advancement of the fourth generation nuclear energy gas-solid spouted beds also have been used for coating TRISO nuclear fuel particles (kernel UO₂) by chemical vapor deposition using four layers of carbon. Conical, cylindrical with cone base, cone-based, and slot-rectangular spouted beds have been studied. Spouted beds have three different regions (spout, fountain, and annular regions) where each region has specific flow behavior that make the hydrodynamic structures of the spouted beds complex. A spouted bed is a solid particles’ bed with a stream of gas jet that is introduces at the bottom from small opening at a speed enough to set the particles in spouted motion. This vertically injection of gas under appropriate conditions will create the three regions; a spout in the center of the bed, a fountain above this spout region, and an annulus where the particles move down toward the spout region and downward in the annular region.

Many studies have been performed on spouted beds by measuring only global hydrodynamic parameters. Therefore, there is a lake in understanding of the effect of design and operating variables on local hydrodynamic quantities such as cross-sectional phases distributions, holdups radial profiles along the bed height, solids velocity, turbulent parameters, gas dispersion, and others. Hence, the focus of this work is to address some of these needs related to the effect of bed size, gas velocity, and particles size and densities on the phases distributions and holdups radial profiles.

In this work two spouted beds have been used; one is 6” spouted bed, and the other is 3” spouted bed. In the 6” spouted bed glass beads particles of 2.45 g/cm³ density at atmospheric pressure have been used. In 3” spouted bed steel particles of 7.4 g/cm³ density at 312 kpa have been applied. Air as the gas phase has been used in those two spouted beds.

In this work Gamma Ray Computed Tomography (CT) has been used to investigate the effect of bed diameter, gas velocity, particles size and density on solids and gas holdups distributions and their radial profiles along the bed height in 3” and 6” diameter gas-solid spouted beds.

The results show that in both beds as gas velocity increases the solids hold up in the spout region increases due to more solids are pulled from the annular region to the spout region as the gas moving upward. However in the annular region the solids hold up remains unchanged when the gas velocity increases. This is because in the annular region the solids are moving downward as a moving bed. In 6” spouted bed diameter the solids hold up in spout region is little higher than that in 3” at the same dimensionless gas velocity which is the ratio of the superficial gas velocity over the minimum spouting velocity.

More results will be presented, discussed and analyzed in this presentation.