Application of fiber optic reflection probes to the measurement of local particle velocity and concentration in gas—solid flow

Herbert, P.M.; Gauthier, Thierry; Briens, Cédric; Bergougnou, M.A.

doi:10.1016/0032-5910(94)02859-1

Cited by 93 publications

(43 citation statements)

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“…The optical fibre sensors are used to measure with a great accuracy pressure [2], mechanical deformation [3], temperature [4] as well as concentration of gases [5], and composition of liquids [6]. However, under harsh environmental conditions, the use of silica glass fibres is difficult due to their poor resistance to mechanical impact and aggressive chemical influences.…”

Section: Introductionmentioning

confidence: 99%

Optical and structural properties of polycrystalline CVD diamond films grown on fused silica optical fibres pre-treated by high-power sonication seeding

et al. 2014

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In this paper, the growth of polycrystalline chemical vapour deposition (CVD) diamond thin films on fused silica optical fibres has been investigated. The research results show that the effective substrate seeding process can lower defect nucleation, and it simultaneously increases surface encapsulation. However, the growth process on glass requires high seeding density. The effects of suspension type and ultrasonic power were the specific objects of investigation. In order to increase the diamond density, glass substrates were seeded using a high-power sonication process. The highest applied power of sonotrode reached 72 W during the performed experiments. The two, most common diamond seeding suspensions were used, i.e. detonation nanodiamond dispersed in (a) dimethyl sulfoxide and (b) deionised water. The CVD diamond nucleation and growth processes were performed using microwave plasma assisted chemical vapour deposition system. Next, the seeding efficiency was determined and compared using the numerical analysis of scanning electron microscopy images. The molecular composition of nucleated diamond was examined with micro-Raman spectroscopy. The sp 3 / sp 2 band ratio was calculated using Raman spectra deconvolution method. Thickness, roughness, and optical properties of the nanodiamond films in UV-vis wavelength range were investigated by means of spectroscopic ellipsometry. It has been demonstrated that the high-power sonication process can improve the seeding efficiency on glass substrates. However, it can also cause significant erosion defects at the fibre surface. We believe that the proposed growth method can be effectively applied to manufacture the novel optical fibre sensors. Due to high chemical and mechanical resistance of CVD diamond films, deposition of such films on the sensors is highly desirable. This method enables omitting the deposition of an additional adhesion interlayer at the glass-nanocrystalline interface, and thus potentially increases transmittance of the optical system.

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Section: Introductionmentioning

confidence: 99%

Optical and structural properties of polycrystalline CVD diamond films grown on fused silica optical fibres pre-treated by high-power sonication seeding

et al. 2014

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“…Non-intrusive methods can be used such as X-ray [25] or gamma-ray measurements [11]. Intrusive methods, using optical fibers for instance [26][27][28], are usually less expensive but very complex too. Such measurements require long development due to their specificity in order to adapt the measurement method to the inherent gas-particle constraints and usually complex data postprocessing is required to get valuable and useful data.…”

Section: Basic Research In the Field Of Fluidization And Transportmentioning

confidence: 99%

Fcc: Fluidization Phenomena and Technologies

Gauthier

Bayle

Leroy

2000

Oil & Gas Science and Technology - Rev. IFP

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Résumé -FCC : phénomènes de fluidisation et technologies -Le procédé de craquage catalytique (FCC) est utilisé dans la majorité des raffineries pour convertir les charges lourdes. Depuis plus de 50 ans, les développements du catalyseur et l'amélioration de la technologie de la zone réactionnelle ont permis une évolution continue de ce procédé, évolution qui n'est sans doute pas terminée, permettant notamment de traiter des charges de plus en plus lourdes. Dans cet article, les moyens nécessaires au développement de technologies adaptées au procédé de craquage catalytique sont discutés à travers les exemples de développement d'un séparateur rapide en tête de riser et d'un échangeur de chaleur permettant de refroidir le catalyseur pendant la régénération. Les aspects liés à l'écoulement de catalyseur fluidisé à travers la zone réactionnelle sont également abordés. NOTATIONS Main SymbolsA cross sectional area, m 2 C concentration, mol/m 3 D diameter, m F mass flow rate, kg/s H height, m k pressure drop constant K pressure drop constant M ratio of the particle mass flow rate over gas mass flow rate N number of CSTRs P pressure, Pa PB pressure balance, Pa R radius, m Q volumetric flow rate, m 3 /s U velocity, m/s V superficial velocity, m/s W mass flux, kg/s/m 2 X axial position, m ε holdup of a given phase τ time constant, s ρ density, kg/m 3 Subscripts b related to fluidized bed conditions br bubble velocity relative to suspension c related to cyclone d related to dipleg conditions dn related to dipleg conditions for negative pressure separators dp related to dipleg conditions for positive pressure separators G related to gas flowing to the separator gas exit g related to gas I related to inlet conditions i related to intersticial gas mf related to minimum fluidization conditions mb related to minimum bubbling fluidization conditions p related to particle s related to gas flowing to the separator dipleg sg related to gas for superficial velocity sl related to slip between gas and particles sk related to skeletal t related to tracer tc related to tapped conditions in defluidized conditions.

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“…Although numerous investigations have utilized fiber optic probes for obtaining direct measurements of solid concentration (Louge 1997;van Ommen and Mudde 2008), several works have noted the inefficacy of the fiber optic probe to give absolute concentration values due to the problematic calibration procedures involved (Matsuno, Yamaguchi et al 1983;Herbert, Gauthier et al 1994;. Accordingly, in this work, instead of attempting to FINAL TECHNICAL REPORT 166 calibrate the fiber optic probe signals to obtain absolute solid concentration values (since, for example, continual bombardment of the probe tip by glass particles may alter the baseline signal with time), a wavelet decomposition (Mallat 1998) of the raw signal is instead used as an indicator of relative solid concentration (i.e., dense phase versus dilute phase), as detailed below.…”

Section: Pitot Tube and Extraction Probementioning

confidence: 99%

“…Before discussing which wavelet decomposition scale is appropriate to use as the threshold for cluster detection, it is worth noting that efforts have been made by previous researchers towards calibrating the voltage signals obtained from fiber optic probes to obtain solids concentration traces (Louge 1997; van Ommen and Mudde 2008). Nonetheless, several works have noted the inefficacy of the fiber optic probe to give absolute concentration values due to the associated problematic calibration (Matsuno, Yamaguchi et al 1983;Herbert, Gauthier et al 1994;. Consequently, in this work, instead of calibrating the fiber optic probe signals to obtain quantitative values (magnitudes) for solids concentration, the raw voltage traces were instead analyzed for relative changes in concentration (via wavelet analysis) in order to obtain information on clustering.…”

mentioning

confidence: 99%

“…The underlying principle of the fiber optic probe is such that a higher voltage signal is obtained from the receiving fiber when light emitted from the light-source fiber is blocked, as occurs when the probe is surrounded by a denser (particle-rich) phase. On the other hand, a lower voltage signal is obtained when light from the emitter is relatively unobstructed, which occurs when the probe tip is in a more dilute (gas-rich) phase.Although numerous investigations have utilized fiber optic probes for obtaining direct measurements of solid concentration (Louge 1997; van Ommen and Mudde 2008), several works have noted the inefficacy of the fiber optic probe to give absolute concentration values due to the problematic calibration procedures involved (Matsuno, Yamaguchi et al 1983;Herbert, Gauthier et al 1994;. Accordingly, in this work, instead of attempting to 166 calibrate the fiber optic probe signals to obtain absolute solid concentration values (since, for example, continual bombardment of the probe tip by glass particles may alter the baseline signal with time), a wavelet decomposition(Mallat 1998) of the raw signal is instead used as an indicator of relative solid concentration (i.e., dense phase versus dilute phase), as detailed below.…”

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confidence: 99%

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Development, Verification, and Validation of Multiphase Models for Polydisperse Flows

Hrenya¹,

Cocco²,

Fox³

et al. 2011

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This report describes in detail the technical findings of the DOE Award entitled "Development, Verification, and Validation of Multiphase Models for Polydisperse Flows." The focus was on high-velocity, gas-solid flows with a range of particle sizes. A complete mathematical model was developed based on first principles and incorporated into MFIX. The solid-phase description took two forms: the Kinetic Theory of Granular Flows (KTGF) and Discrete Quadrature Method of Moments (DQMOM). The gas-solid drag law for polydisperse flows was developed over a range of flow conditions using Discrete Numerical Simulations (DNS). These models were verified via examination of a range of limiting cases and comparison with Discrete Element Method (DEM) data. Validation took the form of comparison with both DEM and experimental data. Experiments were conducted in three separate circulating fluidized beds (CFB's), with emphasis on the riser section. Measurements included bulk quantities like pressure drop and elutriation, as well as axial and radial measurements of bubble characteristics, cluster characteristics, solids flux, and differential pressure drops (axial only). Monodisperse systems were compared to their binary and continuous particle size distribution (PSD) counterparts. The continuous distributions examined included Gaussian, lognormal, and NETLprovided data for a coal gasifier.FINAL TECHNICAL 4 DE-FC26-07NT43098 5 EXECUTIVE SUMMARYThis report is the final technical report for the award DE-FC26-07NT43098 entitled "Development, Verification, and Validation of Multiphase Models for Polydisperse Flows." Below is a summary of work completed under the grant for each of the major goals. Goal I: Continuum Theory for Solid PhaseTwo separate and complementary continuum theories were derived to model polydisperse solids: the kinetic theory of granular flow (KTGF) and the discrete quadrature method of moments (DQMOM). Both theories are based on first principles with no adjustable parameters. The polydisperse KTGF and DQMOM were then encoded in MFIX, and underwent a wide range of verification testing to ensure, to the best possible extent, that no coding errors were present. These verification tests included both granular and gas-solid flows, including cases where an analytical solution and/or DEM (discrete element method) data and/or simple test cases. For the case of KTGF, another set of constitutive equations were derived which rigorously incorporated the gas phase for a simplified case of monodisperse systems at low Reynolds numbers. This derivation used the acceleration model developed in Task 2 from direct numerical simulations (DNS) in the starting kinetic equation, and indicated the effect of the fluid phase on the resulting constitutive relations. Goal II: Improved Gas-Particle Drag Laws -effect of particle size distributionIn this portion of the effort, two types of direct numerical simulations (DNS) were used to extract the drag force experienced by particles in a polydisperse suspension. These two methods, na...

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Application of fiber optic reflection probes to the measurement of local particle velocity and concentration in gas—solid flow

Cited by 93 publications

References 10 publications

Optical and structural properties of polycrystalline CVD diamond films grown on fused silica optical fibres pre-treated by high-power sonication seeding

Optical and structural properties of polycrystalline CVD diamond films grown on fused silica optical fibres pre-treated by high-power sonication seeding

Fcc: Fluidization Phenomena and Technologies

Development, Verification, and Validation of Multiphase Models for Polydisperse Flows

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