Quantitative tomographic measurements of opaque multiphase flows

George, D. L.; Torczynski, J. R.; Shollenberger, K. A.; O’Hern, Timothy J.; Ceccio, Steven L.

doi:10.2172/752051

Cited by 14 publications

(20 citation statements)

References 27 publications

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“…Additional phase distribution measurements were made with an EIT system developed collaboratively by Sandia National Laboratories (Torczynski et al, 1997;George et al, 1998b) and the University of Michigan that has been calibrated for two-phase measurements using the Sandia GDT system. Details of the design and implementation of this system have been described in detail by George et al (2000) and will be summarized here.…”

Section: Electrical-impedance Tomography (Eit)mentioning

confidence: 99%

Three-phase material distribution measurements in a vertical flow using gamma-densitometry tomography and electrical-impedance tomography

George¹,

Shollenberger²,

Torczynski³

et al. 2001

International Journal of Multiphase Flow

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---Experiments are presented in which electrical-impedance tomography (EIT) and gammadensitometry tomography (GDT) measurements were combined to simultaneously measure the solid, liqui~and gas radial distributions in a vertical three-phase flow. The experimental testbed was a 19.05-cm diameter bubble column in which gas is injected at the bottom and exits out the top while the liquid and solid phases recirculate. The gas phase was air and the liquid phase was deionized water with added electrolytes. Four different particle classes were investigated for the solid phase: 40-100 pm and 120-200 pm glass beads (2.41 g/cm3), and 170-260pm and 200-700pm polystyrene beads (1.04 g/cm3), Superficial gas velocities of 3 to 30 cmk and solid volume fractions up to 0.30 were examined. For all experimental conditions investigated, the gas distribution showed only a weak dependence on both . particle size and density. Average gas volume fraction as a fimction of supert3cial gas velocity can be described to within &O.04by a curve passing through the center of the data. For most cases the solid particles appeared to be radially uniformly dispersed in the liquid.

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Section: Electrical-impedance Tomography (Eit)mentioning

confidence: 99%

Three-phase material distribution measurements in a vertical flow using gamma-densitometry tomography and electrical-impedance tomography

George¹,

Shollenberger²,

Torczynski³

et al. 2001

International Journal of Multiphase Flow

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“…An existing EIT system designed for use in nonconductive vessels (George et al 2000c) was modified for this study so that it could be employed in metallic vessels. This modified system was first used in a proof-of-concept experiment to measure the height of a packed bed of nonconducting solid particles submerged inside a liquid-filled steel standpipe (Liter et al 2002).…”

Section: Contentsmentioning

confidence: 99%

“…In addition, the expensive cost and operation, and the added human-protection requirements of a GDT system are impractical for widespread industrial use, especially if a less expensive and safer EIT system is capable of making the same two-phase measurements, and making them more quickly. The authors have also used EIT in combination with GDT to obtain quantitative measurements of phase-volumefraction distributions for three-phase flows in nonconducting vessels (George et al 1999;George et al 2001a;George et al 2000c).…”

Section: Summary Of Previous Workmentioning

confidence: 99%

“…Brief reviews of the hydrodynamics and modeling of multiphase flows in vertical bubble columns can be found in the literature (George et al 2000c;Shah and Deckwer 1983;Torczynski et al 1997). Here, a brief review of the theories behind EIT and GDT measurements is presented.…”

Section: Theorymentioning

confidence: 99%

“…The original EIT system, data acquisition procedure, and reconstruction have been described in detail by George et al (George et al 2000b;George et al 2000c;George et al 2000d) and are briefly summarized here. To measure the electrical conductivity field within a domain, a set of electrodes in contact with the domain is used.…”

Section: Electrical-impedance Tomography (Eit)mentioning

confidence: 99%

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Electrical-Impedance Tomography for Opaque Multiphase Flows in Metallic (Electrically-Conducting) Vessels

Liter¹,

Torczynski²,

Shollenberger³

et al. 2002

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A novel electrical-impedance tomography (EIT) diagnostic system, including hardware and software, has been developed and used to quantitatively measure material distributions in multiphase flows within electrically-conducting (i.e., industrially relevant or metal) vessels. The EIT system consists of energizing and measuring electronics and seven ring electrodes, which are equally spaced on a thin nonconducting rod that is inserted into the vessel. The vessel wall is grounded and serves as the ground electrode. Voltage-distribution measurements are used to numerically reconstruct the time-averaged impedance distribution within the vessel, from which the material distributions are inferred. Initial proof-of-concept and calibration was completed using a stationary solid-liquid mixture in a steel bench-top standpipe. The EIT system was then deployed in Sandia's pilot-scale slurry bubble-column reactor (SBCR) to measure material distributions of gas-liquid two-phase flows over a range of column pressures and superficial gas flow rates. These two-phase quantitative measurements were validated against an established 3 gamma-densitometry tomography (GDT) diagnostic system, demonstrating agreement to within 0.05 volume fraction for most cases, with a maximum difference of 0.15 volume fraction. Next, the EIT system was combined with the GDT system to measure material distributions of gasliquid-solid three-phase flows in Sandia's SBCR for two different solids loadings. Accuracy for the three-phase flow measurements is estimated to be within 0.15 volume fraction. The stability of the energizing electronics, the effect of the rod on the surrounding flow field, and the unsteadiness of the liquid temperature all degrade measurement accuracy and need to be explored further. This work demonstrates that EIT may be used to perform quantitative measurements of material distributions in multiphase flows in metal vessels.

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