Pressure fluctuation measurements and flow regime transitions in gas‐liquid‐solid fluidized beds

Fan, Liang‐Shih; Satija, Sunil; Wisecarver, Keith

doi:10.1002/aic.690320227

Cited by 36 publications

(18 citation statements)

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“…Studies on pressure fluctuations in multiphase reactors have been carried on for several years. Fan et al (1986) characterized the flow regimes in a fluidized bed by the statistical properties of the wall pressure fluctuations, especially the power spectral density function and the root mean square of the pressure fluctuations. Vial et al (2000) found that the kurtosis of PFS exhibited a pronounced maximum at transition point from homogeneous to heterogeneous regime in bubble column or airlift reactor.…”

Section: Introductionmentioning

confidence: 99%

Origin of pressure fluctuations in an internal-loop airlift reactor and its application in flow regime detection

Zhang

2009

Chemical Engineering Science

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Section: Introductionmentioning

confidence: 99%

Origin of pressure fluctuations in an internal-loop airlift reactor and its application in flow regime detection

Zhang

2009

Chemical Engineering Science

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“…Investigation of bubble behavior would provide a basic knowledge for the analysis of hydrodynamic phenomena of the fluidized beds. Therefore, many researchers have recently paid attention to this aspect (Fukuma et al, 1987; Han and Kim, 1990), though the effect of flow regimes has not been discussed in their work.Moreover, it has been found that flow regimes in a threephase fluidized bed depend mainly upon operating conditions (Muroyama et al, 1985;Fan et al, 1986;Chen et al, 1995a), and the bubble behavior is significantly different in different flow regimes. However, surprisingly little work has been found in the literature concerning the effect of flow regimes on bubble behavior.…”

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confidence: 99%

Local bubble behavior in three‐phase fluidized beds

Chen

Feng

et al. 1998

Can J Chem Eng

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Bubble behavior, including bubble Sauter diameter, bubble rise velocity, bubble frequency and local gas holdup in different radial and axial positions, was measured using a dual electro-conductivity probe in air-water-glass beads fluidization systems. It has been found that the bubble characteristics differ significantly in various flow regimes, depending on the operating conditions; the radial distribution of bubble parameters also changes from one flow regime to another. Thus, it is necessary to employ local bubble behavior in the modeling of three-phase fluidized beds.Le comportement des bulles, et notamment le diametre des bulles de Sauter, la vitesse d'ascension des bulles et la retention de gaz locale dans des positions radiales et axiales differentes, a ete mesure a I'aide d'une sonde d'electroconductivite duale dans des systemes de fluidisation a billes air-eau-verre. On a trouve que les caracteristiques des bulles variaient de faqon significative dans divers regimes d'ecoulement selon les conditions de fonctionnement; la distribution radiale des parametres des bulles change avec le regime d'ecoulement. C'est pourquoi le comportement des bulles local est a inclure dans la modelisation des lits fluidises triphasiques.Keywords: bubble behavior, fluidization, three-phase fluidized bed, flow regime.n the modeling of three-phase fluidized-bed reactors, bub-I ble characteristics such as bubble size, bubble rise velocity and local gas holdup, are of fundamental importance. On the other hand, bubbles play a major role on the flow structure and phase holdups in the beds. Investigation of bubble behavior would provide a basic knowledge for the analysis of hydrodynamic phenomena of the fluidized beds. Therefore, many researchers have recently paid attention to this aspect (Fukuma et al., 1987; Han and Kim, 1990), though the effect of flow regimes has not been discussed in their work.Moreover, it has been found that flow regimes in a threephase fluidized bed depend mainly upon operating conditions (Muroyama et al., 1985;Fan et al., 1986;Chen et al., 1995a), and the bubble behavior is significantly different in different flow regimes. However, surprisingly little work has been found in the literature concerning the effect of flow regimes on bubble behavior.The present work is aimed at an investigation into local bubble behavior in different flow regimes under various operating conditions by means of a dual electro-conductivity probe. The effect of flow regimes on the bubble behavior is discussed. ExperimentalExperiments were carried out in a Plexiglas column with a 0.285 m inside diameter and a 4.1 m height in air-tap water-glass beads systems. The distributor is shown in Figure 1. It was found that the orifice size of gas passageway on the distributor has a remarkable effect on the flow pattern: the large diameter of the orifices would result in an early onset of the turbulent bubble regime (TBR) without undergoing the homogeneous bubble regime (HBR) or the *Author to whom correspondence should be addressed. transiti...

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“…This will benefit several different areas of work associated with fluidized beds, including issues related to hydrodynamic and heat-transfer similitude, 1,2 chemical processes occurring in fluidized beds, 3,4 and the use of pressure fluctuations as a diagnostic tool for the fluidized bed's performance and fluidization regime identification. [5][6][7][8] The testing and analysis methods used to evaluate fluidized-bed pressure fluctuations have varied widely among researchers. Brue and Brown investigated sampling and analysis techniques traditionally used to measure and interpret pressure fluctuations.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Pressure Fluctuations in Fluidized Beds

Falkowski

Brown

2004

Ind. Eng. Chem. Res.

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Pressure fluctuations were measured in a fluidized bed and evaluated in the frequency domain. The objective of this research was to determine the effect of bed parameters on the power spectra from the corresponding pressure fluctuations. The motivation for this work is to develop pressure fluctuations as a diagnostic tool for fluidized-bed reactors and combustors. Pressure fluctuation data for a range of bed heights, fluidization velocities, particle sizes, particle densities, and bed temperatures were taken to determine the effect of these parameters on the power spectrum. The dominant frequency was a function of the height of the fluidized bed. Secondary peaks were not influenced by the height of the bed, although they did depend on the position of the probe in the bed. Peaks in power spectra were observed to shift in frequency as the gas superficial velocity through the bed was changed. Powders of different classification had distinctive power spectra. Group A powders behaved like first-order linear systems; group B powders showed similarities to second-order linear systems; and group D powders exhibited harmonic behavior in their power spectra. When pressure fluctuations were measured over a temperature range from ambient to above 500 °C, power spectra varied little when the ratio of the superficial velocity to the minimum fluidization velocity was held relatively constant. Pressure fluctuations were measured in a fluidized bed and evaluated in the frequency domain. The objective of this research was to determine the effect of bed parameters on the power spectra from the corresponding pressure fluctuations. The motivation for this work is to develop pressure fluctuations as a diagnostic tool for fluidized-bed reactors and combustors. Pressure fluctuation data for a range of bed heights, fluidization velocities, particle sizes, particle densities, and bed temperatures were taken to determine the effect of these parameters on the power spectrum. The dominant frequency was a function of the height of the fluidized bed. Secondary peaks were not influenced by the height of the bed, although they did depend on the position of the probe in the bed. Peaks in power spectra were observed to shift in frequency as the gas superficial velocity through the bed was changed. Powders of different classification had distinctive power spectra. Group A powders behaved like first-order linear systems; group B powders showed similarities to second-order linear systems; and group D powders exhibited harmonic behavior in their power spectra. When pressure fluctuations were measured over a temperature range from ambient to above 500°C, power spectra varied little when the ratio of the superficial velocity to the minimum fluidization velocity was held relatively constant.

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Pressure fluctuation measurements and flow regime transitions in gas‐liquid‐solid fluidized beds

Cited by 36 publications

References 5 publications

Origin of pressure fluctuations in an internal-loop airlift reactor and its application in flow regime detection

Origin of pressure fluctuations in an internal-loop airlift reactor and its application in flow regime detection

Local bubble behavior in three‐phase fluidized beds

Analysis of Pressure Fluctuations in Fluidized Beds

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