Characterization of fluidization regimes by time-series analysis of pressure fluctuations

Johnsson, Filip; Zijerveld, RC; Schouten, JC Jaap; Bleek, CM van den; Leckner, Bo G

doi:10.1016/s0301-9322(99)00028-2

Cited by 386 publications

(357 citation statements)

References 56 publications

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“…In addition, bubbling beds can be further divided into three different modes of contact: single bubble, multiple bubble and exploding bubble (Johnsson et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…This quantification is an appropriate measurement method, as is time-series analysis of the fluctuation signals measured. According to Johnsson et al (2000), the time-series analysis for this purpose can be made in time domain, frequency domain (spectral analysis) or state-space domain (chaos analysis) and the measurements are normally made by one of two methods, differential (two points on the wall column) or absolute (one point) mode (Werther, 1999).…”

Section: Introductionmentioning

confidence: 99%

“…From the point of view of subsequent application in industry, the two main objectives of the intense study of the time-sampling pressure measurements in real time in fluidized beds are the identification and monitoring of the different fluidization regimes (DiMattia et al, 1997;Zijerveld et al, 1998;van Ommen et al, 1999;Trnka et al, 2000;Kage et al, 2000;Johnsson et al, 2000;Brown and Brue, 2001) and the demarcation of the transition points between regimes (Hong et al, 1990;Wilkinson, 1995;Bi and Grace, 1995;Bai et al, 1996;Zijerveld et al, 1998). In the first case, the aim was to identify a pattern in the pressure fluctuation behavior for each fluidization state, distinguishing between them with the aid of quantitative methods of time-series analysis.…”

Section: Introductionmentioning

confidence: 99%

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Time series analysis of pressure fluctuation in gas-solid fluidized beds

Felipe

Rocha

2004

Braz. J. Chem. Eng.

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-The purpose of the present work was to study the differentiation of states of typical fluidization (single bubble, multiple bubble and slugging) in a gas-solid fluidized bed, using spectral analysis of pressure fluctuation time series. The effects of the method of measuring (differential and absolute) pressure fluctuations and the axial position of the probes in the fluidization column on the identification of each of the regimes studied were evaluated. Fast Fourier Transform (FFT) was the mathematic tool used to analysing the data of pressure fluctuations, which expresses the behavior of a time series in the frequency domain. Results indicated that the plenum chamber was a place for reliable measurement and that care should be taken in measurement in the dense phase. The method allowed fluid dynamic regimes to be differentiated by their dominant frequency characteristics.

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“…In addition, bubbling beds can be further divided into three different modes of contact: single bubble, multiple bubble and exploding bubble (Johnsson et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Time series analysis of pressure fluctuation in gas-solid fluidized beds

Felipe

Rocha

2004

Braz. J. Chem. Eng.

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“…Therefore, the distributor and the bed pressure drops during experiments were of the same order. Under similar conditions Johnsson et al [23] and Sasic et al [24] showed that bed operates under the multiple bubble regime and the bed and the air-supply system are independent.…”

Section: Experimental Set-upmentioning

confidence: 93%

“…In order to avoid influences of the air-supply system in the bubble eruption pattern, the distributor pressure drop must be high enough to assure that the bed and the air-supply system are uncoupled [23,24]. In this way, the distributor used during experiments was a perforated plate with 110 holes 1 mm in diameter with a 1 cm The gas pressure drop through the bed is P bed 4000 Pa and the superficial gas velocity during experiments was around 1 m/s.…”

Section: Experimental Set-upmentioning

confidence: 99%

Experimental observations on the different mechanisms for solid ejection in gas-fluidized beds

Almendros-Ibáñez

Sánchez-Delgado

Sobrino

et al. 2009

Chemical Engineering and Processing: Process Intensification

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a b s t r a c tThis work presents an experimental study of the ejection velocity for different mechanisms of solid ejection in fluidized beds. The experiments were carried out in a 2D fluidized bed, where the bubble eruptions were recorded with a frequency of 250 frames per second using a high speed video camera with a resolution of 1.3 Megapixels.The results show that in isolated bubble eruption, the dome velocity is significantly reduced by the effect of a group of raining particles in the form of stalactites within the bubble. Higher velocities are observed when bubble coalescence takes place. If bubbles coalesce before the leading bubble breaks, the momentum of the trailing bubble together with the increase in the throughflow accelerate the dome of the leading bubble. In contrast, when coalescence occurs after the breakage of the leading bubble, the wake of the trailing bubble is projected into the freeboard with a very high velocity (wake spike mechanism). The last observed mechanism, the jet spike mechanism, occurs when a stream of bubbles reaches the bed surface following the path opened by the previous bubbles. A cloud of particles moving upward is observed, although their velocities are not as high as in the wake spike mechanism due to the interchange of momentum during the collisions with other particles.Finally, an explanation for some of the patterns of gas release from erupting bubbles recently observed by Hartung et al.

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