Measurement of overall solids mass flux in a gas–solid Circulating Fluidized Bed

Bhusarapu, Satish; Fongarland, Pascal; Al‐Dahhan, Muthanna H.; Duduković, Milorad P.

doi:10.1016/j.powtec.2004.09.007

Cited by 32 publications

(26 citation statements)

References 14 publications

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“…Only one source is used, either in combination with a single detector (single beam arrangement, Weimer et al, 1985, Mudde et al, 1999, Bhusarapu et al, 2004 O"Hern et al, 2005, Tortora et al, 2006. The former requires a single traverse through the slice of interest; the latter provides these data in one capture.…”

Section: X-ray and Gamma-ray Tomographymentioning

confidence: 99%

Measuring the Gas-Solids Distribution in Fluidized Beds -- A Review

Ommen¹,

Mudde²

2008

International Journal of Chemical Reactor Engineering

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In gas-solid fluidized beds, the distribution of the particles typically varies both in time and space. Since the gas-solids distribution and its variation have a strong influence on the performance of a fluidized bed for a given process, it is very important to accurately measure the gas-solids or voidage distribution. This paper reviews techniques for measuring the voidage distribution in gas-solid fluidized beds, with a focus on the developments during the last ten years. We will treat subsequently direct visualisation, tomography, optical probes, capacitance probes, and pressure measurements.Dense gas-solids flows are typically opaque to visible light. This makes optical techniques only of limited use in dense gas-solids flow. However, direct visualization can be useful for very dilute systems, pseudo 2-D beds, and the outer layer of dense, 3-D systems. Tomography is frequently used to obtain the voidage distribution in a horizontal cross-section of the bed. Electric capacitance tomography is fast, but its spatial resolution is limited and image reconstruction is still troublesome. Although some steps forward have been made, research is continuing at this point. For nuclear (X-ray and gamma-ray) tomography, the image reconstruction is much easier and the spatial resolution better, but its temporal resolution is typically much lower. Therefore, research efforts for nuclear tomography are mainly aimed at increasing the measurement frequency. Optical probes determine the voidage as a function of time in a small measurement volume, either by the degree of reflection or by the degree of transmission of a light bundle. Capacitance probes determine the voidage as a function of time in a small measurement volume by measuring the dielectric permittivity of the gas-solids suspension in the measurement volume. Both optical and capacitance probe techniques are reasonably well-developed; the current research effort spent at improving them seems * We would like to thank M.O. Coppens, J. Nijenhuis, R.W.S Bohlken, and M.A. Wormsbecker for useful suggestions during preparation of this manuscript. limited, especially for capacitance probes. Time-averaged pressure measurements are commonly used to determine the average bed density and bed height. By sampling the local pressure at a sufficiently high frequency (typically in the order of 200 Hz), much more information can be obtained about the fluidized bed hydrodynamics. However, obtaining quantitative voidage data from pressure fluctuations measurement remains a difficult task; in-bed pressure fluctuation (and acoustic) measurements are mostly used to determine changes in the voidage dynamics and distribution.

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Section: X-ray and Gamma-ray Tomographymentioning

confidence: 99%

Measuring the Gas-Solids Distribution in Fluidized Beds -- A Review

Ommen¹,

Mudde²

2008

International Journal of Chemical Reactor Engineering

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“…Fig. 8 shows a typical measurement setup of a gamma-ray densitometer on a downcomer [105]. A radiation source and a detector are aligned on a carriage that is moved around the downcomer to scan different chords through the cross-section of the column.…”

Section: Gamma-ray Densitometrymentioning

confidence: 99%

“…The tracer trajectory was also used to characterize the particle-wall contacting parameters and the friction factor [178][179][180]. Based on the particle backflow phenomenon in a riser, Bhusarapu et al [105,146,181] measured the solids circulation rate, overall solids flux and turbulent parameter profiles. More dynamic properties were characterized by processing the RPT signals through statistical analysis, non-linear dynamics analysis, symbolic dynamics analysis and data mining [182][183][184].…”

Section: Radioactive Particle Trackingmentioning

confidence: 99%

“…The signal series of porosity fluctuation was further processed by a deterministic chaos analysis method. It was found that the attractor dimension was basically consistent with that of the pressure fluctuation signal.Bhusarapu et al[105] estimated the solids mass flux in a CFB loop through a gamma-ray densitometer in combination with the radioactive particle tracking (RPT) technique. The former was used to measure the cross-sectional averaged solids hold-up while the latter was to obtain the solids velocity from the time of flight measurement of the radioactive tracer traversing the axial distance between the detectors.…”

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confidence: 99%

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Non-intrusive measurement and hydrodynamics characterization of gas–solid fluidized beds: a review

Sun

Yan

2016

Meas. Sci. Technol.

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“…For a monoenergetic beam of radiation, the intensity of a transmitted gamma ray beam (I) follows Lambert-Beer's law [11][12][13][14][15] …”

Section: Theoretical Considerationsmentioning

confidence: 99%

Gamma transmission system for detection of scale in oil exploration pipelines

Oliveira

Nascimento

Marinho

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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a b s t r a c tThe goal of this study is to detect and quantify the thickness of the scale layer inside the service pipelines. For this purpose, a system composed of a 137 Cs source and a NaI(Tl) scintillation detector was developed. The source and the detector were positioned in geometry to make transmission measurements. A computational routine was developed to generate simulated data, which were later compared with the experimental ones, in order to calculate the thickness of scale layer. The results of the validation tests show similar values to the real ones. It was therefore possible to conclude that the procedure is efficient for the detection and quantification of materials inside pipelines, and that the system is advantageous for its application in the field, especially with respect to radioprotection.

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Measurement of overall solids mass flux in a gas–solid Circulating Fluidized Bed

Cited by 32 publications

References 14 publications

Measuring the Gas-Solids Distribution in Fluidized Beds -- A Review

Measuring the Gas-Solids Distribution in Fluidized Beds -- A Review

Non-intrusive measurement and hydrodynamics characterization of gas–solid fluidized beds: a review

Gamma transmission system for detection of scale in oil exploration pipelines

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