Identification of defluidization in fluidized bed coating using the Gaussian spectral pressure distribution

Fluidized bed with a rotating distributor operated under defluidization conditions

“…Later, water-induced defluidization experiments are presented for both aspect ratios (h b /D = 0.75 and h b /D = 1.5) and compared with the reference nominal conditions. The signal used to monitor the rotating distributor effect on the fluidized bed was based on the pressure fluctuation measurements recorded by the sensor placed at the plenum [24,29]. Fig.…”

“…Spectral analyses permit to identify the dominant frequencies characterizing the measured pressure fluctuations time-series [29,30]. The power spectral density of the input pressure signal is estimated using averaged modified periodogram method of spectral estimation.…”

Wide band energy analysis of fluidized bed pressure fluctuation signals using a frequency division method

“…Characteristic features of the power spectrum have been used for the description of the fluidization regime. For example, the frequency peak and the dominant frequency have been used to detect defluidization in coating and drying processes (Parise et al, 2011;de Martin et al, 2011). The coherent standard deviation and the average frequency of pressure fluctuations have also been used to estimate the bubble size and to detect the regime transitions in slurry bubble columns Ruthiya et al, 2005).…”

Monitoring and control of coating and granulation processes in fluidized beds – A review

“…Measurements are easy to assess; they only require transmitters installed at appropriate locations, usually in the plenum chamber, as this location provides an overview of bubbles and particles movement throughout fluidization. Researches focusing on the hydrodynamic monitoring of fluidized beds and which are based on the processing of pressure fluctuation signals have been widely accepted by the international scientific community due to their great potential of application in the identification of agglomeration in the processes, such as: gasification and biomass combustion [9][10][11][12][13], coke production [14] and coating and granulation of solid particles in a fluidized bed [15][16][17][18][19][20]. The papers of Johnsson et al [4] and van Ommen et al [21] report many results on the monitoring of fluidization regimes employing various methods of analysis of pressure fluctuation signals, besides describing in detail such analysis.…”

“…Through the non-linear adjustment of pressure spectra to an exponential function similar to the regular Gaussian distribution function, the defluidization could be analyzed through significant changes to the Gaussian mean frequency profiles obtained. Silva et al [35] and Parise et al [17] used the Gaussian spectral analysis methodology and applied it to identify the initial moments of the defluidization of the microcrystalline cellulose particles, analyzing the moisturizing (atomization of distilled water) and coating (atomization of an aqueous polymeric with Eudragit Ò ) processes, respectively. Fig.…”