A research partnership

between Boise State

University, Idaho

National Laboratory,

Idaho State University

and University of Idaho.

Center for Advanced Energy Studies

Experimental Studies of OxygenSparging in Molten Salt Through aTransparent Furnace

Experimental Studies of OxygenSparging in Molten Salt Through aTransparent Furnace

Ryan W. Bezzant and Supathorn PhongikaroonChemical Engineering Department and Nuclear

Engineering Program

University of Idaho, Idaho Falls

Center for Advanced Energy Studies

Michael F. SimpsonPyroprocessing Technology Department,

Idaho National Laboratory

Ryan W. Bezzant and Supathorn PhongikaroonChemical Engineering Department and Nuclear

Engineering Program

University of Idaho, Idaho Falls

Center for Advanced Energy Studies

Michael F. SimpsonPyroprocessing Technology Department,

Idaho National Laboratory

Alternative Proposed ProcessesChopped Fuel

Uranium MetalMetal Waste

Ceramic Waste

Electrorefiner andProduct

Refinement

Ion Exchange Zone Freezing

High PurityElectrolyte

High PurityElectrolyte

Contaminated Electrolyte

Rare Earth Oxidative Precipitations

• MotivationThere is a lack of fundamentalstudy to provide insight intosystematic parameters in moltensalt

• ApproachUse transparent cell, high speedcamera and O2 sensor to obtainconcentration data, bubbledistribution and reaction rates.

Motivation and Approach

23223

2223

223

Cl2

3ORE

2

1ORECl3

Cl2

3REOORECl2

ClREOClO2

1RECl1

Korea Atomic Energy

Research Institute (KAERI)

observed gravity separation

of oxides in molten salt.1

1Yung-Zun Cho, Gil-Ho Park, Dae-Seok Han, Han-Soo Lee, and In-Tae Kim. Journal of Nuclear Science and Technology, 46,2009, 1004-1011;Yung-Zun Cho, Hee-Chul Yang, Gil-Ho Park, Han-Soo Lee, In-Tae Kim. Journal of Nuclear Materials, 384, 2009, 256-261;Yong-Jun Cho, Hee-Chul Yang, Hee-Chul Eun, Eung-Ho Kim, and In-Tae Kim. Journal of Nuclear Science and Technology,43, 2006, 1280-1286.

Experimental Setup and Plans

Oxygen FlowController

High SpeedDigital Camera

TransparentFurnace

Gas CoolingTube

OxygenSensor

HalogenLamp andStrobe Light

Sparging Tube

• Melt 150 g of LiCl-KCl eutectic salt (58.5 mol% LiCl, 41.5 mol% KCl) at500C under an argon environment.

• O2 Sparging Rates: (8.33 10-7, 1.67 10-6, 2.50 10-6, 3.33 10-6 ) m3/s.Note: (0.05, 0.10, 0.15, 0.20) L/min.

• Record bubble images (250 fps) and O2 concentration data ( 3%).• Sparge until salt is O2 saturated.

Corrosion Issues

304 Stainless Steel

Inconel 600

Non-porous Alumina(Aluminum oxide)3/16” OD 0.031”holes.

Solution

Obstacles

Bubble Dispersion Video

Temperature: 500⁰ C Camera Speed: 250 fps

Sparging Rate: 8.33 10-7 m3/s Sample Size: 150 g

Transparent Study Analysis

Bubble velocity is also observed.

Bubble measurement Midas OS Imaging

3/1

EllipsoidEquivalent

2SmalleargLEllipsoid

V6

b

bb6

V

Sparging rate,Q

(m3/s)

Number meandiameter, b10

(m)

Numberstandard

deviation, σ10

(m)

Volume meandiameter, b30

(m)

Sauter meandiameter, b32

(m)

8.33 × 10-7 0.00263 0.00073 0.00301 0.00304

1.67 × 10-6 0.00368 0.00112 0.00421 0.00438

2.50 × 10-6 0.00383 0.00118 0.00466 0.00455

3.33 × 10-6 0.00407 0.00103 0.00451 0.00459

Bubble Shape Validation

/VdRe

/gM

/dgEo

bequiv

324

2equiv

Conditions of Curve

Log M= -10

Eotvos Number 0.2-40

Reynold’s Number 300-4000

Experimental Results

Log M= -10.1304

Eotvos Number 0.54-8.94

Reynold’s Number 344-2406

[7]

100

1000

10000

0.5 1 2 4 8 16

Rey

nol

ds

Nu

mb

er,

Re

Eotvos Number, Eo

8.33 E-7

1.67 E-6

2.50 E-6

3.33 E-6

Log M=-10

Sparging Ratem3/s

Salt viscosity,μc (N s/m2)

Salt density,ρc (kg/m3)

Surface tension,σc (N/m)

Oxygen density,ρb (kg/m3)

0.00223 1,621 0.126 0.457

Bubble Size Distributions

0.0

0.3

0.6

0.9

1.2

1.5

1.8

0 1 2

Pro

ba

bil

ity

Den

sity

Fu

rnct

ion

Normalized Bubble Diameter, b

0.0

0.2

0.4

0.6

0.8

1.0

0 1 2

Cu

mu

lati

ve

Nu

mb

erF

req

uen

cy

Normalized Bubble Diameter, b

8.33 E-7

1.67 E-6

2.50 E-6

3.33 E-6

Gaussian Curve

Sparging Rate(m3/s)

The normally distributed probability density function:

2

2

1exp

2

1)(f

018.0255.0027.0004.1b

b

10

and

Fanning Friction RatioSpargingRate, Q(m3/s)

Mean BubbleRising

Velocity, Vb

(m/s)

StandardDeviation

(m/s)

8.33 × 10-7 0.262 0.05101.67 × 10-6 0.301 0.09982.50 × 10-6 0.299 0.05543.33 × 10-6 0.338 0.0770

0.00001

0.0001

0.001

0.01

300 3000

Fa

nn

ing

Fri

ctio

nR

ati

o,

f/R

e b

Bubble Reynolds Number, Reb

8.33 E-7

1.67 E-6

2.50 E-6

3.33 E-6

Sphere

Fit (Eq. 9)

Sparging Ratem3/s

c

bc

bc

c

b V

g

3

4

Re

f

35.1b

b

Re29.6Re

f

Using this correlation, the rising

velocity of a bubble can be

estimated based on the equivalent

diameter of a bubble.

Oxygen Gas Holdup, f

Sparging rate, Q(m3/s)

Experimental(Dimensionless)

Akita and Yoshida(Dimensionless)

Difference(%)

8.33 × 10-7 0.00169 0.00174 3.09

1.67 × 10-6 0.00294 0.00345 17.4

2.50 × 10-6 0.00427 0.00514 19.2

3.33 × 10-6 0.00523 0.00681 30.3

Experimental Approach:

Akita and Yoshida’s Correlation (1973):

2b

S

D

Q4

V

V

SVand

Fr

068.0

c

b086.0Ga

121.0Bo4

NNN32.0)1(

c

c2

Bo

gDN

Bond Number

2c

3

Ga

gDN

2/1S

FrgD

VN

Galileo Number Froude Number

• Calculate the interfacial area of an averageequivalent bubble:

• Oxygenation model:

• After integration with the I.C. t = 0, C = C0:

32b

6a

k = Mass Transfer Coefficient

C* = Concentration at saturation

C0 = Initial concentration

C = Concentration at specific time

φ = Gas hold up

a = Interfacial area

Vs = Superficial gas velocity

Vb = Bubble rise velocity

Q = Gas flow rate

D = Crucible diameter

b32 = Sauter mean diameter

)CC()1(

ka

dt

dC *

t

1

ka)CCln()CCln( 0

**

O2 Mass Transfer Coefficient

Plot and Resulting k values

0.70

0.75

0.80

0.85

0.90

0.95

1.00

0 20 40 60 80

ln((

C*-

C0)

/(C

*-C

))

Time (s)

8.33 E-7

1.67 E-6

2.50 E-6

3.33 E-6

Sparging Ratem3/s

Sparging rate,Q (m3/s)

Slope,ka/(1-F)

(s-1)

Interfacialarea, a

(m-1)

Mass transfercoefficient, k

(m/s)

95%Confidence

Interval (%)8.33 × 10-7 0.0032 3.33 0.00096 18.91.67 × 10-6 0.0029 4.03 0.00072 18.92.50 × 10-6 0.0035 5.63 0.00068 26.23.33 × 10-6 0.0027 6.82 0.00039 14.7

Diffusion Coefficient• Use the experimental k value to predict DL .

• Use 3 correlations based on two different frames of preferences: (1)physics of the bubble and (2) systematic physical properties.

Penetration theory:

b

322

LV4

bkD

Calderbank and Moo-Young (1960):3/23/1

c3/1

c2

L )g/(kD

Akita and Yoshida (1973): )g/(DkD 08.0c

16.0c

66.006.024.0c

26.02L

Sparging Rate( m3/s )

Diffusion coefficients, DL (m2/s)Penetration

TheoryCalderbank and

Moo-YoungAkita andYoshida

8.33 × 10-7 8.40 × 10-9 1.28 × 10-8 2.43 × 10-8

1.67 × 10-6 5.89 × 10-9 7.21 × 10-9 1.42 × 10-8

2.50 × 10-6 5.82 × 10-9 6.43 × 10-9 1.30 × 10-8

3.33 × 10-6 1.65 × 10-9 2.12 × 10-9 4.44 × 10-9

Conclusion

• Both bubble size and rise velocity with in oxygen sparging rate.

• b10 ranged from 0.00263 m to 0.00407 m.

• These bubbles form an ellipsoidal shape and the equivalent bubblediameters of the populations observed were normally distributed.

• The bubble rise velocities can be predicted using a Fanning frictionfactor-Reynolds number correlation.

• k can be calculated experimentally using the oxygenation model andranged from 3.94 × 10-4 m/s to 9.61 × 10-4 m/s.

• The results show trend with sparging rate or bubble size whichis supported by observations reported by previous researchers(Calderbank et al., 1960; Kulkarni, 2007).

• Diffusion coefficients were calculated using three correlations andcompared.

• Penetration theory is the most robust of these models yieldingdiffusivity values between 1.65 × 10-9 m2/s and 8.40 × 10-9 m2/s,which is supported by literature (Cussler, 1984; Sada et al., 1984).

Acknowledgement

• US Department of Energy/Idaho Nationallaboratory/Battelle Energy Alliance-Drawdown Project .

• Center for Advanced Energy Studies for the use of theRadiochemistry Laboratory.

• Michael Shaltry, Robert Hoover and Ammon Williamsfor experimental and technical supports.