Fluidised bed dynamics diagnosis from measurements of low-frequency out-bed passive acoustic emissions

Briongos, Javier Villa; Aragón, José M.; Palancar, María C.

doi:10.1016/j.powtec.2005.12.009

Cited by 38 publications

(22 citation statements)

References 32 publications

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“…A better estimate of U mf for Geldart B particles is obtained using a second method consisting on measuring the pressure fluctuations in the bed [21][22][23]. Fig.…”

Section: Minimum Fluidization Velocitymentioning

confidence: 99%

Fluidization of Group B particles with a rotating distributor

et al. 2008

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A novel rotating distributor fluidized bed is presented. The distributor is a rotating perforated plate, with 1% open-area ratio. This work evaluates the performance of this new design, considering pressure drop, Δp, and quality of fluidization. Bed fluidization was easily achieved with the proposed device, improving the solid mixing and the quality of fluidization.In order to examine the effect of the rotational speed of the distributor plate on the hydrodynamic behavior of the bed, minimum fluidization velocity, U mf , and pressure fluctuations were analyzed. Experiments were conducted in the bubbling free regime in a 0.19 m i.d. fluidized bed, operating with Group B particles according to Geldart's classification. The pressure drop across the bed and the standard deviation of pressure fluctuations, σ p , were used to find the minimum fluidization velocity, U mf . A decrease in U mf is observed when the rotational speed increases and a rise in the measured pressure drop was also found. Frequency analysis of pressure fluctuations shows that fluidization can be controlled by the adjustable rotational speed, at several excess gas velocities.Measurements with several initial static bed heights were taken, in order to analyze the influence of the initial bed mass inventory, over the effect of the distributor rotation on the bed hydrodynamics.

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“…A better estimate of U mf for Geldart B particles is obtained using a second method consisting on measuring the pressure fluctuations in the bed [21][22][23]. Fig.…”

Section: Minimum Fluidization Velocitymentioning

confidence: 99%

Fluidization of Group B particles with a rotating distributor

et al. 2008

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“…Those acoustic techniques are later applied as active or as passive methods (Cents et al, 2004;Herrera et al, 2002;Boyd and Varley, 2002). With regard to the passive acoustic emission in which the signal collected is created by the fluidizing process itself, acoustics measurements have been reported by either placing the sensor inside (Zukowski, 2001) or outside the vessel (Briongos et al, 2006b;Cody et al, 1996;Finney et al, 1998). In spite of the initial advantages of the external acoustic measurements (non invasive and low imple mentation cost), they present some problems.…”

Section: Introductionmentioning

confidence: 99%

“…To the best of the authors' knowledge, there are few works in literature that use advanced techniques over external passive acoustic signals for getting low frequency information (Briongos et al, 2006b;Finney et al, 1998). Besides, those previous works deal with the unwanted slugging regime.…”

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

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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.

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“…Most of these works use a very high sampling frequency, which leads to a large amount of data and limits the use of advanced techniques (like phase space analysis) due to the high computational cost required. To the best of the authors' knowledge, there are few works in literature which use advanced techniques over external passive acoustic signals for getting low frequency information [10,15,16], being the sensibility of the acoustic sensors a limitation for collecting some useful information.…”

Section: Introductionmentioning

confidence: 99%

“…The poor signal/noise ratio obtained in [15] led to the use of new high sensibility acoustic sensors in order to obtain a signal with better quality. In [17] was reported that by using high sensitivity accelerometers is possible to get a low frequency signal related to bulk and bubble dynamics.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2011

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a b s t r a c tLow frequency accelerometry signals have been applied for detecting regime transitions in a gas solid fluidized bed. Three solids have been fluidized to promote bubbling, churn and slugging regime. The Kolmogorov entropy and the power spectral density have been used to determine the regime transitions as well as to analyze the dynamical features characterizing the different regimes. Pressure and external acceleration measurements have been taken simultaneously. The accelerometry signal was sampled at 10 kHz; then, the envelope was extracted and resampled at 400 Hz. Pressure signal was sampled at 10 kHz and resampled at 400 Hz. Two problems were found during the work: the colored noise present in the envelope and the lack of low frequency information for one of the tested solids. FIR, wavelet and EMD filter strategies have been applied to remove the noise present in the envelope. It is concluded that the envelope of the accelerometry signal might be used to detect regime transition in the same way as the pressure fluctuation signals. Both Kolmogorov and spectral analysis exhibit common features to those obtained from pressure signal analysis, supporting the hypothesis of using low frequency accelerometry instead of conventional pressure measurements for monitoring fluidized beds.

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Fluidised bed dynamics diagnosis from measurements of low-frequency out-bed passive acoustic emissions

Cited by 38 publications

References 32 publications

Fluidization of Group B particles with a rotating distributor

Fluidization of Group B particles with a rotating distributor

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

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

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