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Electrical-Impedance Tomography for Opaque Multiphase Flows in Metallic (Electrically-Conducting) Vessels - November 2002

Liter, Scott Gayton
Torcynski, John R.
Shollenberger, Kim A.
Ceccio, Steven L.

Sandia National Laboratories

In this pdf format, this document has 84 pages and is 2.06MB.

Table of Contents

Figures 6
Tables 8
Nomenclature 8

1

Background and Introduction

11
 

1.1

Overview and Motivation 11

1.2

Measurement Techniques 12

1.3

Summary of Previous Work 14

2

Theory

14
 

2.1

Electrical-Impedance Tomography (EIT) 14

2.2

Gamma-Densitometry Tomography (GDT) 19

2.3

Combined EIT and GDT for Three-Phase Measurements 21

3

Diagnostic Systems

24
 

3.1

EIT Apparatus 24

3.2

GDT Apparatus 26

4

Experiments

27
 

4.1

Benchtop Validation Test 27

4.2

Sandia's Slurry Bubble-Column Reactor (SBCR) Facility 29

4.3

Experimental Procedure for Measurement in Sandia's SBCR 32

4.4

Experimental Material Properties 34

4.5

Sources of Uncertainty 35

5

Experimental Results and Discussion

36
 

5.1

Benchtop Validation Measurements 36

5.2

Two-Phase Measurements 37

5.3

Three-Phase Measurements 45

6

Conclusions and Future Recommendations

52

References

53

Appendix

56
 

LIST OF FIGURES

Figure 1

Schematic of an EIT system applied to an electrically insulating (nonconducting) vessel 16

Figure 2

Schematic of an EIT system applied to an electrically conducting vessel 17

Figure 3

Photograph of verification experiment showing the EIT electronics, the electrode rod with seven copper ring electrodes (the top eight ring shown is a plastic seal), and the standpipe 25

Figure 4

Photographs of the circuit boards inside the EIT electronics box 26

Figure 5

A schematic of the GDT system in the horizontal plane 27

Figure 6

Schematic of verification experiment consisting of an electrode rod inserted coaxially in an electrically conducting standpipe filled with nonconducting solid polystyrene particles and liquid 28

Figure 7

Photograph of the Sandia slurry bubble-column reactor facility. Also shown is the vault for the gamma source mounted on the two-axis automated traverse 29

Figure 8

Photograph of a cross sparger similar to that used in this study to inject air into the bottom of the bubble column 30

Figure 9

Schematic of EIT system applied to Sandia's slurry bubble-column reactor (SBCR). Shown on the right is a photograph of the SBCR (0.48-mID). The bottom left shows predictions of voltage contours in a cross-section of the SBCR for two cases, one of constant conductivity in the top half, and one of variable conductivity in the bottom half 31

Figure 10

(a) Computational mesh corresponding to one-quarter of the interior of the SBCR with the EIT rod inserted along a diameter. (b) Voltage contours computed for a uniform electrical conductivity throughout the domain with current injection from electrode 4 33

Figure 11

Plot of the EIT reconstructed particle-bed height versus the measured particle-bed height in the steel standpipe 36

Figure 12

Comparison of symmetric radial gas volume fraction profiles from EIT and GDT for a column pressure colp = 103 kPa and a superficial gas velocity = gu 10 cm/s 39

Figure 13

Comparison of symmetric radial gas volume fraction profiles from EIT and GDT for a column pressure colp = 103 kPa and a superficial gas velocity = gu 15 cm/s 39

Figure 14

Comparison of symmetric radial gas volume fraction profiles from EIT and GDT for a column pressure colp = 103 kPa and a superficial gas velocity = gu 20 cm/s 40

Figure 15

Comparison of symmetric radial gas volume fraction profiles from EIT and GDT for a column pressure colp = 103 kPa and a superficial gas velocity = gu 25 cm/s 40

Figure 16

Comparison of symmetric radial gas volume fraction profiles from EIT and GDT for a column pressure colp = 207 kPa and a superficial gas velocity = gu 10 cm/s 41

Figure 17

Comparison of symmetric radial gas volume fraction profiles from EIT and GDT for a column pressure colp = 207 kPa and a superficial gas velocity = gu 15 cm/s 41

Figure 18

Comparison of symmetric radial gas volume fraction profiles from EIT and GDT for a column pressure colp = 207 kPa and a superficial gas velocity = gu 20 cm/s 42

Figure 19

Comparison of symmetric radial gas volume fraction profiles from EIT and GDT for a column pressure colp = 207 kPa and a superficial gas velocity = gu 25 cm/s 42

Figure 20

Comparison of symmetric radial gas volume fraction profiles from EIT and GDT for a column pressure colp = 310 kPa and a superficial gas velocity = gu 10 cm/s 43

Figure 21

Comparison of symmetric radial gas volume fraction profiles from EIT and GDT for a column pressure colp = 310 kPa and a superficial gas velocity = gu 15 cm/s 43

Figure 22

Comparison of symmetric radial gas volume fraction profiles from EIT and GDT for a column pressure colp = 310 kPa and a superficial gas velocity = gu 20 cm/s 44

Figure 23

Plot of the bulk-averaged gas fraction as a function of superficial gas velocity and column pressure, from GDT measurements 44

Figure 24

Plot of the bulk-averaged gas fraction as a function of superficial gas velocity and column pressure, from EIT measurements 45

Figure 25

Radial material phase-volume-fraction profiles for a nominal slurry concentration 0%, with a column pressure colp = 103 kPa and a superficial gas velocity nom= gu 10 cm/s. 47

Figure 26

Radial material phase-volume-fraction profiles for a nominal slurry concentration 0%, with a column pressure colp = 207 kPa and a superficial gas velocity nom= gu 10 cm/s. 48

Figure 27

Radial material phase-volume-fraction profiles for a nominal slurry concentration 4%, with a column pressure colp = 103 kPa and a superficial gas velocity nom= gu 10 cm/s. 48

Figure 28

Radial material phase-volume-fraction profiles for a nominal slurry concentration 4%, with a column pressure colp = 207 kPa and a superficial gas velocity nom= gu 10 cm/s. 49

Figure 29

Radial material phase-volume-fraction profiles for a nominal slurry concentration 8%, with a column pressure colp = 103 kPa and a superficial gas velocity nom= gu 10 cm/s. 49

Figure 30

Radial material phase-volume-fraction profiles for a nominal slurry concentration 8%, with a column pressure colp = 207 kPa and a superficial gas velocity nom= gu 10 cm/s. 50

Figure 31

Radial material phase-volume-fraction profiles for a nominal slurry concentration 4%, with a column pressure colp = 103 kPa and a superficial gas velocity = gu 10 cm/s, and calculated with a conductivity ratio ~    41.1 ~ r )( ~ l ~ = 50

Figure 32

Radial material phase-volume-fraction profiles for a nominal slurry concentration 4%, with a column pressure colp = 207 kPa and a superficial gas velocity = gu 10 cm/s, and calculated with a conductivity ratio ~    41.1 ~ r )( ~ l ~ = 51

Figure 33

Radial material phase-volume-fraction profiles for a nominal slurry concentration 8%, with a column pressure colp = 103 kPa and a superficial gas velocity = gu 10 cm/s, and calculated with a conductivity ratio ~    94.0 ~ r )( ~ l ~ = 51

Figure 34

Radial material phase-volume-fraction profiles for a nominal slurry concentration 8%, with a column pressure colp = 207 kPa and a superficial gas velocity = gu 10 cm/s, and calculated with a conductivity ratio ~    94.0 ~ r )( ~ l ~ = 52
 
LIST OF TABLES

Table 1

Various industrial application that would benefit from improved capability to measure spatial volumetric phase fractions 12

Table 2

Some noninvasive diagnostic techniques reported in the literature used to measure spatial volumetric phase fractions 13

Table 3

Operating conditions for the two- and three-phase tests in the SBCR 32

Table 4

Properties of the phase materials used for the material distribution reconstructions 35

Table 5

Measured and predicted particle-bed heights for 6 different tests, 3 with copper electrodes and 3 with stainless steel electrodes 37

Table 6

Comparison of EIT and averaged GDT measurements of gas volume fractions for the 11 different two-phase operating conditions listed in Table 4 38

Table 7

Predicted bulk-averaged phase volume fractions for the 6 three-phase cases measured and listed in Table 4 46

Table 8

Predicted bulk-averaged volumetric phase-fractions for the cases of 4% and 8% nominal solids loading, using a scaled conductivity ratio 47