Investigation of cross-sectional gas-solid distributions in spouted beds using advanced non-invasive gamma-ray computed tomography (CT)

Abstract

The successful operation and safety of the Very-High-Temperature Nuclear Reactors (VHTR) extremely depend on the quality of the TRISO nuclear fuel coated particles. Hence, the fuel coating technology of TRISO particles, based on chemical vapour deposition (CVD) process, performed in gas-solid spouted beds, is of utmost importance. However, the deposition of the coating layers surrounding the kernel is a delicate process, and impacted by the hydrodynamics of spouted beds. Therefore, in this work, we have applied an advanced non-invasive gamma-ray computed tomography (CT) technique for the first time to investigate the hydrodynamics of spouted beds. In particular, we study the effect of particle density, particle size, bed size, and superficial gas velocity on the gas-solid cross-sectional distributions of spouted beds. The color distributions of the cross-sectional images clearly identified the three regions of spouted beds: the spout, the annulus, and the fountain regions. Interesting results and findings are presented, discussed and analyzed in the article. For example, the results demonstrated that the summation that operating spouted beds at stable spouting state would lead to achieving uniform coating layers of the particles in the TRISO fuel coating process is not adequate. Further, it has been found that increasing the superficial gas velocity much higher above the minimum spouting velocity increases the gas holdup in the annulus above the gas holdup value at the loss-packed bed state, contrary to common assumptions presented in the literature. This study represents an original experimental investigation required both for advancing the understanding of TRISO particles spouted bed and providing benchmark data to validate computational fluid dynamics (CFD).

Overcoming the gamma‐ray computed tomography data processing pitfalls for bubble column equipped with vertical internal tubes

“…Figure and Figure exhibit schematic and photographic images of the CT technique with a bubble column equipped with a bundle of vertical internals. The CT technique has been successfully applied to measure the phase holdup distribution in different multiphase flow reactors with various scale sizes at mReal such as 12 in (0.3 m) pebble bed reactor, 6 in (0.152 m) bubble column, 6 in (0.152 m) and 18 in (0.46 m) fluidized beds, and 3 in (0.076 m) and 6 in (0.152 m) spouted bed reactors . Details on the mechanical design, hardware, software, and operation of the CT technique have been discussed elsewhere by Varma .…”

Detecting stability of conical spouted beds based on information entropy theory

“…This means that the number of particles in the spout increase as the particle size decreases. This leads to a longer contact time of small particles with the gas phase [41]. On the other hand, with increasing the particle size, the number of particles contributing to the spout decreases which can improve the stability of the spout due to the fact that the gas momentum dissipation is less when the spout is free of solids.…”

Effect of Operating Parameters on Gas‐Solid Hydrodynamics and Heat Transfer in a Spouted Bed

“…In recent decades, many experiments and calculations have been conducted to reveal the characteristics of gas‐solid two‐phase flows . Additionally, Hosseini et al.…”

“…In recent decades, many experiments and calculations have been conducted to reveal the characteristics of gas-solid twophase flows [13][14][15][16]. Additionally, Hosseini et al [17] evaluated the influence of the radial distribution function on the heattransfer behavior of a 2D spouted bed through the Eulerian-Eulerian two-fluid approach.…”