Flow characteristics in a bubbling fluidized bed at elevated temperature

Hydrodynamics of shallow fluidized bed of coarse particles

“…For efficient designing of these processes hydrodynamics of the bed is of great importance. 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].…”

“…For investigation of hydrodynamics different measurement techniques are applied such as: visual observation and video recording [4], pressure fluctuation measurements [2][3][4]6,7,12], local voidage fluctuation measurements by means of optical fiber probes [13] and electrical capacitance tomography [5]. Also, different approaches for data analysis could be used such as time and frequency domain analysis as well as chaos analysis.…”

“…Frequency domain analysis is useful tool to prove the existence of the same regime in different systems (or under different conditions) by comparing the amplitude spectra in the same range of frequencies [14]. In the frame of chaos analysis, many researchers have used the Kolmogorov entropy in order to characterize fluidization regimes [3,6].…”

Defluidization and agglomeration of a fluidized bed reactor during Cynara cardunculus L. gasification using sepiolite as a bed material

“…The better mixing of biomass with bed material led to the release of volatiles inside the bed, creating endogenous bubbles in addition to the air bubbles formed at the distributor plate. The more bubbles the higher pressure fluctuations due to a greater probability of bubbles coalescence and therefore, larger bubble diameter [45,46]. For u/u mf = 2, 4 and 6 the standard deviation increased around a 50% from the signal at nominal conditions (before biomass feeding), having the higher production of bubbles an important effect.…”

Multiresolution analysis of pressure fluctuations in a gas–solids fluidized bed: Application to glass beads and polyethylene powder systems

“…Further analysis could be performed on the detail coefficient series. The number of peaks (D4 and D5) and peak amplitude may provide information about the bubble frequency [24,25] and bubble diameter [26]. Frequency content of objects could be obtained from wavelet coefficients [1], where smooth coefficients mainly captured the objects of low frequency oscillations (large bubbles) in the pressure signal, and the detail coefficients captured the ones of higher frequency (small bubbles) over the time.…”