Wavelet analysis of pressure fluctuation signals in a bubbling fluidized bed

Lu, Xuesong; Li, Hongzhong

doi:10.1016/s1385-8947(99)00097-2

Cited by 89 publications

(43 citation statements)

References 10 publications

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“…These methods are based on the analysis of ε G data. Other flow regime identification methods are the fractal [319], wavelet [320,321], Hurst's [322,323], spectral and nonlinear chaos [93,320,[324][325][326][327][328][329][330][331][332][333] and Kolmogorov entropy [332][333][334] approaches. Some authors have used methods based on the Shannon entropy, which measures the degree of indeterminacy in a system [335,336].…”

Section: The Flow Regimesmentioning

confidence: 99%

Two-Phase Bubble Columns: A Comprehensive Review

2018

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We present a comprehensive literature review on the two-phase bubble column; in this review we deeply analyze the flow regimes, the flow regime transitions, the local and global fluid dynamics parameters, and the mass transfer phenomena. First, we discuss the flow regimes, the flow regime transitions, the local and global fluid dynamics parameters, and the mass transfer. We also discuss how the operating parameters (i.e., pressure, temperature, and gas and liquid flow rates), the operating modes (i.e., the co-current, the counter-current and the batch modes), the liquid and gas phase properties, and the design parameters (i.e., gas sparger design, column diameter and aspect ratio) influence the flow regime transitions and the fluid dynamics parameters. Secondly, we present the experimental techniques for studying the global and local fluid dynamic properties. Finally, we present the modeling approaches to study the global and local bubble column fluid dynamics, and we outline the major issues to be solved in future studies.

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Section: The Flow Regimesmentioning

confidence: 99%

Two-Phase Bubble Columns: A Comprehensive Review

2018

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“…That fact leads to the use of different techniques focused on identifying and distin guishing those contributions from the measured signal. Thus, the multi scale nature of fluidized bed dynamics has drawn con siderable attention in the last years (Li and Kwauk, 2001;Lu and Li, 1999;Zhao and Yang, 2003;Briongos et al, 2006aBriongos et al, , 2007Abbasi et al, 2009). However, due that the causes and sources of accelerometer signals are not yet understood, the Coherent Output Power, COP, and the Incoherent Output Power, IOP, analysis used in van der Schaaf et al (2002) is applied here as a first approach to analyze the different dynamical components appearing in the envelope process, comparing the local and global information stored in both pressure and envelope accelerometer signals.…”

Section: Frequency Domainmentioning

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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“…All of these studies demonstrated that the methodology of time-series analysis based on chaos theory can provide us with important insights into the complex hydrodynamics of gas-liquid BCs. In addition, different methods such as statistical analysis [24][25][26], power spectrum analysis [27], fractal analysis [28] and wavelet analysis [29,30] have been proposed to successfully describe the dynamic behavior of two-phase flow. None of these previous studies has been focused on the application of the nonlinear chaos analysis to local gas holdup fluctuations for the identification of zones of increased turbulence in the BC.…”

Section: Analogy Between Bubble Columns and Chaotic Systemsmentioning

confidence: 99%

Application of Chaos Analysis for the Investigation of Turbulence in Heterogeneous Bubble Columns

Nedeltchev

2009

Chem Eng & Technol

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The Kolmogorov entropy (KE) algorithm was applied to local gas holdup fluctuations for estimating the degree of turbulence (chaos) in a large-scale bubble column (0.289 m ID and clear liquid height: 1.31 m). The latter was operated with nitrogen and polyalphaolefin liquid (PSS8) in the churn-turbulent regime (0.117 ≤ U g ≤ 0.257 m/s) at both high temperature (T = 441-468 K) and pressure (P = 1.8-2.5 MPa). Measurements in four different zones (z = 0.35, 0.67, 1.1 and 1.52 m) were performed. When the bubble coalescence is weak (local gas holdups < transitional gas holdup), the KE exhibits an initial peak (enhanced turbulence) in the first zone, then a sudden drop in the second zone and finally it increases smoothly in the upper zones. In the case of strong bubble coalescence, the KE exhibits alternating maxima and minima, i.e., instable flow patterns. It was found that at z = 1.52 m, the KE values increase with P. At higher values of T, the KE values are lower in all zones.

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Wavelet analysis of pressure fluctuation signals in a bubbling fluidized bed

Cited by 89 publications

References 10 publications

Two-Phase Bubble Columns: A Comprehensive Review

Two-Phase Bubble Columns: A Comprehensive Review

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

Application of Chaos Analysis for the Investigation of Turbulence in Heterogeneous Bubble Columns

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