Free top fluidized bed surface fluctuations as a source of hydrodynamic data

Briongos, Javier Villa; Soler, Jesús Guardiola

doi:10.1016/s0032-5910(03)00122-0

Cited by 19 publications

(10 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Traditionally, Region 2 has been related to the finer structures of the bed (fast dynamic processes) (Johnsson et al, 2000;van der Schaaf et al, 1999). Finally, the high frequency region involves less than E WB3 ¼ 1% of the energy, proving that Region 3 has no clear dependence on the fluidization regime (Briongos and Guardiola, 2003;Johnsson et al, 2000).…”

Section: Pressure Sensors Rating Effectmentioning

confidence: 99%

“…The easy and fast computation of the wide band energy provides a reliable view of the dynamic behavior of the system once the power spectrum is properly divided into a set of frequency regions (Briongos and Guardiola, 2003;Gómez-Hernández et al, 2012;van der Schaaf et al, 2002van der Schaaf et al, , 2004. Traditionally, this type of frequency division has been conducted using visual selection of the cut-off frequencies between the different spectral regions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Gómez-Hernández

Sánchez-Prieto

Briongos

et al. 2014

Chemical Engineering Science

Self Cite

View full text Add to dashboard Cite

Abstract:A statistical method based on approximation of the cumulative energy distribution by Student's t-distribution is proposed for the unbiased frequency domain division. The proposed method fixes the number of samples needed to estimate the power spectrum and its corresponding cumulative energy distribution using the Kolmogorov-Smirnov test. The reliability of the method to divide the frequency domain was shown for different fluidization velocities by changing the bed aspect ratio and using different pressure probes. Water-induced defluidization tests were conducted to illustrate the use of wide band energy as a monitoring tool. The Student's t-distribution results are compared with an analysis performed using the traditional visual inspection method. The energy of the power spectrum contained within the frequency regions obtained by the visual method is not able to detect changes in the bed aspect ratio or the start of the rotating distributor. No meaningful differences could be observed in the frequency regions using different quality pressure sensors because the approach using Student's t-distribution focuses on the sharp energy increase produced by the primary frequencies of the power spectrum. The sensitivity exhibited by the proposed frequency division approach for the range of fluidization conditions tested improves the use of the energy contained in these regions as a diagnostic tool in fluidized bed processes.

show abstract

Section: Pressure Sensors Rating Effectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Gómez-Hernández

Sánchez-Prieto

Briongos

et al. 2014

Chemical Engineering Science

Self Cite

View full text Add to dashboard Cite

show abstract

“…During the past, a large research effort has been directed towards developing measurement techniques aimed to get knowledge on the dynamic phenomena that take place within the bed (Werther, 1999;Yates and Simons, 1994); some examples are the capacity and the inductance measurements (Brereton and Grace, 1993;Louge and Opie, 1990), techniques based on optic fiber probes (Amos et al, 1996;Zhang et al, 1998), and laser based measurements (Briongos and Guardiola, 2003;Solimene et al, 2007). However, among those techniques, the pressure fluctuations measurements remain as the most used technique (Johnsson et al, 2000;Sasic et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Can low frequency accelerometry replace pressure measurements for monitoring gas-solid fluidized beds?

Martín

Briongos

Aragón

et al. 2010

Chemical Engineering Science

View full text Add to dashboard Cite

a b s t r a c tThis paper is addressed to introduce a methodology based on low frequency accelerometry that can be used for gas solid fluidized bed monitoring, and for dynamic diagnosis purposes. The proposed methodology consists on extracting the low frequency information encoded within an accelerometry signal, by means of the Hilbert transform method. The time and the frequency domain analysis show how this low frequency information is directly related to the conventional pressure fluctuation measurements, providing useful information on bulk and bubble dynamics. The cross correlation and the coherence function analysis between the pressure and the envelope process of the measured accelerometer signals ''E'', exhibit values approaching unity for frequencies ranging between 2 and 4 Hz. This reveals that pressure signals and accelerometry envelope are related processes. The results from the Coherent Output Power, COP, and the Incoherent Output Power, IOP, analysis confirms that both pressure and envelope time series exhibit the same global and local features open the possibility of using low frequency accelerometers instead of conventional pressure transducers for monitoring and for dynamic diagnosis purposes.

show abstract

“…In contrast, the measurement technique used here (Villa-Briongos and Guardiola, 2003) assumes that the measure of free bed surface fluctuations represents the hydrodynamics of the fluidized bed. Bubble motion inside the bed and bubbles escaping from the top cause fluctuations in the bed surface (Baskakov et al, 1986;Yórquez-Ramirez and Duursma, 2000).…”

Section: Validating Fluidized Bed Dynamic Scalingmentioning

confidence: 99%