Characteristics of slugging regime and transition to turbulent regime for fluidized beds of large coarse particles

Abstract

Slugging characteristics, including slug velocity and frequency and the height of the slugging bed, for a slugging bed of four different types of coarse particles ranging from 1 to 7 mm in size are determined based on pressure fluctuation behavior of the bed. The slugging characteristics of coarse particle slugging beds are found to be much different from those of the particle slugging beds reported in the literature. The pressure fluctuation behavior in a coarse particle turbulent bed and the transition velocity from a slugging bed to a turbulent bed is also examined.

Hydrodynamics of shallow fluidized bed of coarse particles

“…Smaller settled bed height corresponds to the lower apparent weight of the emulsion phase and requires lower energy of gas for expansion and breakage of the bubbles. Satija and Fan [11] have also reported lower values of U c for smaller settled bed heights in the fluidized beds of particles ranging 1-7 mm in diameter. Values of transition velocity U c determined from absolute pressure fluctuations data are lower then those from differential pressure fluctuations data for the same conditions (Table 3), which is in agreement with results reported by Bi and Grace [21].…”

“…Also, different approaches for data analysis could be used such as time and frequency domain analysis as well as chaos analysis. Time domain approaches include: (a) observation of the time sequence of measured signal of pressure or voidage fluctuations [1,4,11]; (b) standard deviation analysis [1,2,5,7]; (c) analysis of other statistical moments like skewness and flatness [1], autocorrelation and crosscorrelation functions [11]. Standard deviation analysis is the most common method based on plotting the standard deviation of pressure or voidage fluctuations versus gas velocity where the magnitude of standard deviation is proportional to the bubble size.…”

“…Therefore, many authors have investigated hydrodynamics of circulating and non-circulating fluidized beds of moderate and fine particles [1][2][3][4][5][6][7]. However, fluidized beds of coarse particles (d p > 1 mm) were much less investigated [8][9][10][11].…”

Shannon Entropy Analysis of Dynamic Behavior of Geldart Group B and Geldart Group D Particles in a Fluidized Bed

“…In this phase, the standard deviations have different trends for different Geldart group particles. For superficial gas velocities higher than U c , the standard deviation diagrams show a leveling off for Geldart group B particles (Makkawi and Wright, 2002) and a decreasing for Geldart group D particles (Satija and Fan, 1985;Bi and Fan, 1992) until reaching the transition to the fast fluidization regime. The transition velocities u c and u k obtained by Shannon entropy analysis are equal to those obtained by standard deviation analysis.…”

Detecting regime transitions in gas-solid fluidized beds from low frequency accelerometry signals

“…The frequency domain analysis has been widely applied to characterize fluidization regimes [18,26] and to get knowledge on the physical phenomena that take place inside a fluidized bed [27,28].…”