5-2-3 slurry mixing w pulse jet mixers_perry meyer[1]

8/7/2019 5-2-3 Slurry Mixing w Pulse Jet Mixers_Perry Meyer[1]

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Mixing Sludges & Slurries withPulsed Jets: Some mixing theory &Test Results

MixingMixing SludgesSludges & Slurries with& Slurries withPulsed Jets: Some mixing theory &Pulsed Jets: Some mixing theory &Test ResultsTest Results

Slurry Retrieval, Pipeline Transport & Plugging & Mixing Workshop

January 14 - 18, 2008, Orlando, Florida.

Perry A. Meyer

Pacific Northwest National Laboratory


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2

Unsteady Jet Mixers at HanfordUnsteadyUnsteady Jet Mixers at HanfordJet Mixers at Hanford

Retrieving from storage

Underground, 1 -

2ft risers

Limited access for equipment

2 -

300hp mixer pumps (baseline)

Treating & vitrifying waste

Closed black

cells

No maintenance for 40 years

Rotating horizontal opposed jets Pneumatic pulsed jets


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3

Turbulent JetsTurbulent JetsTurbulent Jets

ujNear Field Far Field

dj

zu(z)

ud A

(z)

High Reynolds number far field

Constant spread angle

Peak & ave. velocity decrease Thrust/force is constant

Flow rate increases (entrainment)

Energy decreases

Constant Reynolds number

q(z) / qj ~ z / d

(z) = z

u(z) = cjujdj/ z

Re (z) = Rede(z)/ej = d / z

F(z) = Fj


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4

Turbulent Jets, cont.Turbulent Jets, cont.Turbulent Jets, cont.

r

(r)

u(r)

Same results for impinging & attaching jets

Different constants

Wall shear stress

True independent of nozzle cross-sectional areaApproximately true in near-far-field transition

Allows one to approximately obtain flow fields, fluxes, forces, etc

Similar relations for dense jets

w (r) ~ uj

2(dj/r)2

z / dj, r / dj = 15 30


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Jets as mixersJets as mixersJets as mixers

Axial flow impeller: ND ~ uj dj/T


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Downward vertical jet mixersDownward vertical jet mixersDownward vertical jet mixers

Centered Jet(s)

~T/2

uT

uuw

Jet rings(s)

uT ~ uj(dj/T)

~ ujdj/ T2

uuw ~ uj Nj (dj/ T) f(H/ T)

tuw ~ T2/ ujdj Nj f2(H/ T)


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GeometryGeometryGeometry

Nozzle geometry Cross-section: No effect in far field- only area counts

Convergence: extra thrust from pressure

Stand-off No effect for h/dj < 6, little effect for h/T


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Intermittent JetsIntermittent JetsIntermittent Jets

Dimensionless pulse timedetermines regime

uS

uP

u

uV

uC

z

Steady

Short pulse

uP

uFLong pulse

Steady

Np = tpud /d

NP

< 4 vortex ring4 < NP

vortex ring with tail

4


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Unsteady effects on mixing/mobilizationUnsteady effects on mixing/mobilizationUnsteady effects on mixing/mobilization

Would like to utilize steady mixing knowledge base Can we find simple corrections for unsteady effects or are we

dealing with fundamentally new phenomena?

Must consider relative time scales Flow establishment/mixing times compared with pulse time

Duty cycle What happens when the jet is off?

Other time scales Erosion rates

Settling rates

Etc.

Two new parameters are introduced Relative pulse volume

Duty cycle


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Pulse jet mixersPulse jet mixersPulse jet mixers

PJMs in the WTP V (range)

N (range) Pvf (range)

DC (range)

Dpjm (range)

T

H

H

djuj

V

Vpjm

uj(t)

tp

tc

Mixing modes drive

refill


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Important parametersImportant parametersImportant parameters

Operational

Geometry

N number jets

Uj jet velocity (peak)dj /T nozzle diam.

p = Vp /V pulse size

DC = tp/tc duty cyclegeometry

Waste physicalconfiguration

Normal/off-normaloperations

Uniform

Settled layers

Physical &

rheologicalproperties


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Pulse Jet Mixing Studies at Battelle/PNNLPulse Jet MixingPulse Jet Mixing Studies atStudies at Battelle/PNNLBattelle/PNNL

Physical regimes Transitional flow

unsteady

Non-settling/non-Newtonian

Settling- wide particle size &density range, agglomerates

Heels- cohesive/non-cohesive In situ gas generation

Mixing requirements Stagnation/caverns

Off-bottom suspension- VJS Vertical distribution

Gas hold-up & release behavior

Scaled testing program Simulant development

Physical/chemical

Transparent/opaque

1/2/3 phase

Testing

Bench scale - 40m3

Single & multi jets

simplified & prototypicgeometries

Scale up Rating, not designing

Similarity, physical,empirical

Instrumentation


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Non-Newtonian PJM Test ProgramNonNon--Newtonian PJM Test ProgramNewtonian PJM Test Program

Technical basis

Develop scaled testing approach Validate approach- limited testing at scales

Rate existing designs

(3 unique designs in WTP)Improved PJM designs

PJM/sparge hybrid designs


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Theory of PJM Operation with Non-Newtonian Materials

Theory of PJM Operation with NonTheory of PJM Operation with Non--Newtonian MaterialsNewtonian Materials

Model problem: Cavernformation Initially gelled material

Representative of restart aftermixing shutdown

Good mixing system willeliminate cavern

Rheological model Static gel formation with shear

strength s Bingham plastic laminar flow

rheology with yield stress 0 andconsistency K Turbulent flow characteristics

determined by high shearconsistency ~K

Shea rStress

(Pa)

Stra in R ate

0

s K

~K

stat ic

laminar

turbulent

Illustrating Rheological Characteristics ofWaste Slurry

Un-yieldedmaterial

Turbulent flow

Distinct

interface

Typical Pulse Jet Mixer System


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Cavern Formation from a Steady JetCavern Formation from a Steady JetCavern Formation from a Steady Jet

Turbulent wall jet

u(z)= cJud d / z

Force balance at staticinterface

f = Cfu2 / 2

HC / T = a(d/T)Re1 / 21/ 2

Re = ud2 / s

ud

HC

T

Cavernboundary

d

Path ofwall jet

Vp

u(z)z

zcTurbulent

mixingcavern

Stagnantmaterial

at zC HC + T / 2 f = s

Reynolds number dependence

C f , cJ = f(Red ) a ~ R ed

Red = udd / k

Yield Reynolds Number


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Theory of PJM Operation in Non-NewtonianMaterials

Theory of PJM Operation in NonTheory of PJM Operation in Non--NewtonianNewtonianMaterialsMaterials

Cavern Formation from aSteady Jet Turbulent jet theory with force

balance at interface predictscavern height

Yield Reynolds number Ratio fluid force to material

strength

Effects of pulsation Ratio PJM drive time to flow

establishment time

Predicted cavern height

Re=u02/

tD/ tss ~ Vp/ d0

3Re

u0

Und istu rbedmater ial

H C

D T

z

u(z)

Turbu lentCavern

z c

Pl ug m otion

Non-dimensional cavern height as a function of yieldReynolds number for a single PJM in Laponite

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 1000 2000 3000 4000 5000

Yield Reynolds Number Re

0.875 inch Steady Jet

1.0 inch Pulse Jet

2.0 inch Pulse Jet

HcDT

= a d0DT

Re 1/ 2

1 exp(c Vpd0

3Re

)

1/ 2

12

Re = u02/s


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Single-PJM Cavern Tests (laponite)SingleSingle--PJM Cavern Tests (PJM Cavern Tests (laponitelaponite))

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 1000 2000 3000 4000 500

2.2cm Steady Jet

2.5cm Pulse Jet5.1cm Pulse Jet

(Eq. 10)

(Eq. 10)(Eq. 10)Norm

alizedCave

rnHeightHC

/T



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Test to Verify Scaled Testing ApproachTest to Verify Scaled Testing ApproachTest to Verify Scaled Testing Approach

1PJM Tests Simulant selection

Verify cavern formation theory

4PJM Tests Downward firing PJMs

Performed at 3 scales

Simulants Laponite

Transparent

Adjustable shear strength

Kaolin/Bentonite Clay Opaque

Adjustable yieldstress/consistency

Test conditions Rheology (20 -120 Pa) Velocity (3-30 m/s)

Types of measurements

Cavern height (Laponite)

Breakthrough velocity (clay &Laponite)

Upwell velocity (clay)

u0

HC

DT

TurbulentCavern

BreakthroughLocation

Upwell

Velocity

H

v


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Small Scale Test StandsSmall Scale Test StandsSmall Scale Test Stands

Battelle 1/4-scale 4PJM Test Vessel

34 in. diameter

250 gallons

Acrylic vessel

Compressedair/vacuum PJMdrive system

SRNL 1/9-scale 4PJM Test Vessel

17 in. diameter

~30 gallons

Acrylic vessel

Compressedair/vacuum PJMdrive system


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Large-Scale Test Stand at BattelleLargeLarge--Scale Test Stand at BattelleScale Test Stand at Battelle

Battelle 336 4 PJM TestVessel

~13 ft. diameter, ~12,000gallons

Steel construction

Prototypic AEACompressed air PJM drivesystem

Pulse tube prior toinstallation

24 in. diameter

2 in. conical nozzle


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Scaling Data ComparisonsScaling Data ComparisonsScaling Data Comparisons

Comparison of cavern position for tanks of 3 different scales with

Laponite simulant.

Comparison of cavern position for tanks of 3 different scales wiComparison of cavern position for tanks of 3 different scales withth

Laponite simulant.Laponite simulant.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 200 400 600 800 1000 1200 1400 1600 1800


Non-dimen

sionalCavernH

eightHc/D

336

APEL

SRS

Break Through 336APEL Break Through

SRS Break Through

)Linear (336

)Linear (APEL

)Linear (SRS


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Scaling Data ComparisonsScaling Data ComparisonsScaling Data Comparisons

Comparison of surface breakthrough velocity for tanksof 3 different scales with Laponite & clay simulants.

Comparison of surface breakthrough velocity for tanksComparison of surface breakthrough velocity for tanksof 3 different scales with Laponite & clay simulants.of 3 different scales with Laponite & clay simulants.

Laponite Breakthrough

Clay Breakthrough

Laponite Breakthrough

Clay Breakthrough


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Gas hold-up & release- tests at 3 scalesGas holdGas hold--up & releaseup & release-- tests at 3 scalestests at 3 scales

0

1

2

0 50 100 150

APEL 2-25-04 (18 Pa, 14 cP)336 7-22-04 (20 Pa, 18 cP)SRNL 12/13/03 (16 Pa, 19 cP)

RetainedGas(vol%)

Time (min)

0

2

4

6

8

10

12

0 100 200 300 400

SRNL 12/13/03 (1:9 - 16 Pa)

APEL 12/02/03 (1:4.5 - 20 Pa)

336 7/23/04 (1:1 - 20 Pa)

RetainedGas(vol%)

Number of PJM Cycles


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Baseline DesignsBaseline DesignsBaseline Designs

UC

I Cavern only

III Breakthrough with slowperipheral movement

II Breakthrough,

frozenzones

IV Full turbulent mixing


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Improved PJM designsImproved PJM designsImproved PJM designs


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Air sparging in Bingham Plastic SlurryAirAir spargingsparging in Bingham Plastic Slurryin Bingham Plastic Slurry

0

20

40

60

80

100

120

140

160

0 10 20 30 40 50 60

118"118"

83"83"

66"66"

ROBZOI

Avg.

C

haracteristicDiameter(DROB,

DZOI;in)

Flow (Q, ACFM)

DZOI = 34Q0.34

DROB = 11Q0.34

(DZOI + DROB)/2=22Q0.34

Cone Tank Bottom

Liquid Surface

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

0 10 20 30 40 50 60 70 80Distance from Cente r of Tank (in.)

Tank

Elevation

(in.)

40 acfm15 acfm5 acfmSparge TubeLiquid SurfaceTank Wall

DS

ROB

ZOI

2/3 ZOI

SPARGE

TUBE

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 5 10 15 20

206 acfm

68 acfm

GasVolume

(vol%)

Time (min)


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PJM/air-sparge hybrid designsPJM/airPJM/air--spargesparge hybrid designshybrid designs

59 1/8 in. Diameter

PJM Tube

Recirculation PumpDischarge Line

70 in. Diameter

Recirculation PumpSuction Line

40 Sparger

16 1/2 in. Diameter

61 3/4 in. Diameter30 in. Diameter40

48

Recirculation PumpDischarge Line

37In

14 3/4in17 1/8in

45

Perimeter PJM

1 1/4in1 1/4 in

Center PJM

Pump DischargeLine

34in

3 7/8in

~ 4 in

Pump Suction Line


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Final Design Mixing PerformanceFinal Design Mixing PerformanceFinal Design Mixing Performance

PJM Only PJMs + SpargingPJMs + Pump (1 Disch. Noz) Linear (PJM Only)

10-1

100

10-2

10-1

LS 35-36 PaHSLS 33-43 PaQSLS 32 Pa AZ+AFAQSLS 13 Pa AZ+AFAQSLS 3 Pa AZ+AFA

QSLS 34 Pa Clay

QSLS 13 Pa Clay

GasVolumeFractio

n(vol%)

Superficial Velocity (mm/s)


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M3- Rating WTP Mixing SystemsM3M3-- Rating WTP Mixing SystemsRating WTP Mixing Systems

Rate mixing system designs for balance of WTP vessels Normal operations & mixing restart

Broad range of potential waste conditions Non-cohesive (settling) solids - cohesive solids

Wide range of solids size, density, slurry rheology

18 different vessel/mixing system geometriesPrimary metrics Off-bottom suspension

Vertical solids distribution Blend times

Work in 3 phases: non-cohesive, cohesive, gas handling


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Preliminary tests with non-cohesive solidsPreliminary tests with nonPreliminary tests with non--cohesive solidscohesive solids

Simulants Glass spheres (low grade), S ~ 2.47

3 sizes: ds = 63-100, 150-210, 600-800m 2 solids loadings: s = 0.005 & 0.015

Vessel geometries 34-in., 1/13.4-scale of HLP-22

12 tubes, 0.3 & 0.45-in nozzles (4 & 6-in. full scale)

Operational Pulse volume fraction p = 0.025 - 0.10 Duty cycle: DC = 0.18, 0.36, 0.5, 1 (steady)

Measurements Ujs & peak cloud height


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Some off-bottom suspension resultsSome offSome off--bottom suspension resultsbottom suspension results

y = 19.20x -

y = 33.36x -

y = 25.69x -

y = 34.73x -

3

5

7

9

3 4 5 6 7

Nozzle Diameter, dj (equiv. plant scale, in.)

pulsed, 0.5% solids pulsed, 1.5% solids

steady, 0.5% solids steady, 1.5% solids

y = 3.46x -

y = 5.72x

-

3

4

5

6

7

0.00 0.25 0.50 0.75 1.00Duty Cycle, DC

4-in. 6-in.

y = 3.75x -

y = 1.99x -

2

3

4

5

6

7

8

0.00 0.05 0.10 0.15

Pulse Volume Fraction, fp

4-in. pulsed, DC=0.18 4-in. pulsed, DC=0.33

6-in. pulsed, DC=0.18 6-in. pulsed, DC=0.33

4 in. Steady 6 in. Steady

y = 1.24x 0.23

y = 0.96x 0.27

y = 0.22x 0.49

1

10

100 1000Volume Mean Particle Diameter, dS (mm)

DC=0.18 DC=0.33 DC=1.0, Steady

Preliminary data for information only


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Correlating just-suspended velocityCorrelating justCorrelating just--suspended velocitysuspended velocity

Assume Zwietering values for un-tested parameters

Ucs= k(H/

D )

0.14

g

0.5

(s1)

0.43

(

D )

1.3

(ds)a5 (dj )

a6 (100ss )a7 (DC)a8 (p /(1+ p))

a9

D =D/

Steady Pulsed

k 0.78 0.23

ds 0.47 0.26

dj -1.3 -1.06

Ss 0.23 0.34

DC - -0.06

p - -0.18



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Data correlation: off-bottom suspensionData correlation: offData correlation: off--bottom suspensionbottom suspension

Steady Ujs

y = 1.00x +

0.00

R2 = 0.97

0

2

4

6

8

10

0 2 4 6 8 10

measred Ucs

Unsteady Ujs based on peak. v

y = 1.00x +

0.01

R2 = 0.97

0

2

4

6

8

10

0 2 4 6 8 10

measred Ucs

Suggests pulsation effects small at low concentration

Scale-up to plant conditions: design likely inadequate

More testing at additional scales & higher solids required



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Cloud height dataCloud height dataCloud height data

0.25

0.50

0.75

1.00

1.25

2 3 4 5 6 7 8Jet Velocity (

DC=1 DC=0.5 DC=0.33 DC=0.1

0.25

0.50

0.75

1.00

1 2 3 4 5 6 7 8

Jet Velocity (m

100 micron pulsed 200 micron pulsed 800 micron puls

100 micron steady 200 micron steady 800 micron stea



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Simple energy argument Energy per pulse ~ change in potential energy of solids

pFH ~

s

d FH =

u2

2(s1)gHc

HC

D~ F

D

pd

sF

D=

u2

2(s1)gD

Attempt correlation of the form

HCD

~ FDa1p

a2d

a3s

a4include ds /D or us / u

Correlating cloud-heightCorrelating cloudCorrelating cloud--heightheight



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k U s d ds/T p DC

Steady 2.8 2 -0.56 1.7 -1.1 - -

Pulsed 7.1 2 -1.1 1.0 -0.5 0.3 0.25

Correlation of cloud-height dataCorrelation of cloudCorrelation of cloud--height dataheight data

Correlation of pulsed-jet cloud-height

y = 1.00x - 0.01

R2

= 0.95

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Hc/ T - 0.25

Correlation of steady-jet cloud-heig

y = 1.00x + 0.1

R2

= 0.94

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Hc/ T -0.25



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Summary of findingsSummary of findingsSummary of findings

Just suspended velocity

Unsteady effects minor DC effects negligible

There is evidence this breaks down at higher concentrationwhere time to suspend > drive time

Similar solids size effect Concentration exponent 2x

Effect of nozzle size as expected

To be sure, need more data


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Summary, cont.Summary, cont.Summary, cont.

Vertical distribution

Strong bulk density stratification effect Unsteady effects appear to dominate

Exponents on DC & PVF

Fundamental behavior

Weak solids size dependence: Define UJH (just to H). Then UCH ~ ds

0.25

Strong concentration effect: UCH~ s 0.5

Strong pulsation effect: UCH~ p -0.5

5-2-3 slurry mixing w pulse jet mixers_perry meyer[1]

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