S1_11_10_Robert_Maron_rev.pdf

8/9/2019 S1_11_10_Robert_Maron_rev.pdf

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ON-LINE MEASUREMENT OFRHEOLOGICAL PARAMETERS FOR

FEEDBACK CONTROL

Alex van der Spek, Zdoor BV, The Netherlands

Bob Maron, CiDRA Minerals Processing, USA


2/20

Objective• Client motivation: Water and land reclamation from existing tailings

impoundment

• CiDRA motivation: develop on-line rheology “measurement” with existingtechnology

2

Mature Fine Tailings,

non-Newtonian slurry

flocculant

Newtonian slurry, large

solids + water carrier fluid

Recovered

water

solids

Short pipe “reactor”

• Technical Goal:

• Constraints:

• velocity high enough for throughput, adequate mixing of flocculant, and...

• velocity low enough to NOT break down flocks after they form, and...

• Correct flocculant dosage to achieve agglomeration


3/20

On-line rheology measurement

methods investigated

1. Monitor velocity profile change

2. Measure wall shear rate from velocity profile, assume

rheological model, cross plot vs wall shear stress from

pressure drop

3. Monitor degree of turbulence from energy spectrum of

vorticity


4/20

Key concept

length scales and flow

4

Solid particlesVortical structures

If...

Vortical Structure size>>

solid particle size

...Then

NO INTERACTION


5/20

Key concept

length scales and flow

5

Solid particlesVortical structures

If...

Vortical Structure size ≈ solid particle size

...Then

INTERACTION !!


6/20

Length scales and energy propagationKolmogorov Theory of homogeneous isotropic turbulence

Max vortical

length scale,

pipe diameter

≥ vortical

length scalerange

Min vortical

length scale,

Kolmogorov

length scale,

~200 um

≥ >>

Constant bulk velocity, energy propagation

Turbulent vortices transport energy from larger to shorter length scales (vortices)

heatmechanical

energy

6

1000 100 10 1 0.1 0.01

Length scale (mm)

Particle size,

fines

~ 40 um max


7/20

7

Amplifiers and

Digitizers

Sensor Array

∆ ∆ ∆ ∆ ∆ ∆ ∆

∆

∆ ∆

∆ ∆

∆

∆

∆

L = Velocity

∆T

Velocity

Measurement via

Tracking of

VorticalStructures

Vortical Structures - use in SONARtrac

Volumetric Flow Measurement

Rev 10


8/20

Slope of RidgeDetermines Flow

Velocity

Size2Velocity/Length2


1/λ1

U/λ1

U/λ3

1/λ3/λ2

U/λ2

Wave Number

F r e q u e n c y

Temporal / Spatial Decomposition

Wavenumber-frequency (K-ω

plot

Each spatial wavelength has a discrete

temporal frequency ( Frequency= Velocity/ Length -> f=U/λ


Frequency

Sonar Array Processing for Volumetric Flow

8


9/20

Kolmogorov Theory predicts Vortical power spectra...

is measured by Sonar array

9

=

⁄ *

⁄

=1

∗ ∗ ( )

Where,

Sonar array infers (by direct measurement) Power Spectra vs wavenumber, therefore...

Can evaluate energy dissipation (i.e. rheology information) rate without differential pressure

Wavenumber k (1/ft)

F r e q u e n c y ( H z )


10/20

Kolmogorov Theory

Vortical power spectra

10

= 2

3� −5

3� Wavenumber k (rad/ft)

P o w e r ( d B )

r e 2 0 u P a

Wavenumber k (rad/ft)

Power vs wavenumber spectra follow Kolmogorov Theory

F r e q u e n c y ( H z )


11/20

Sonar array measures Vortical Power Quality

11

High Vortical

Power Quality =

low loss

propagation of

coherent power

Rev 10

Same velocities, but different Power Quality Spectra vs Wavenumber

Low Vortical

Power Quality =

high loss

propagation of

coherent power


12/2012

Sonar flow profile meter

Vortical Power Quality (and flow) at 5 heights

Coherent StCoherent StV 90°

V 180°

V 0°

V 45°

V 135°

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20 2.40

CAUDAL (m/seg)

A L T U R A

( N O R M

A L I Z A D A

profile

Reference flow rate

profile side sensor

V 0°

V 45°

V 90°

V 135°

V 180°


13/20

Test setup

Velocity profile,

non-Newtonian

Bingham flow, Velocity profile,

Newtonian

Turbulent flow,

with agglomerated

solids

Mature Fine Tailings

Non-settling fines

agglomerationLarge flocks in water-

based carrier fluid

water

solids

mixer

flowShort pipe “reactor”

13

Sonar

flow

profile

Sonar

flow

profile

Sonar

flow

profile

Flocculant

injection


14/20

14

NO flocculant, non-Newtonian flow

Non-Newtonian Bingham flow

No velocity profile change

With flocculant, Newtonian flow

NO velocity profile change top-bottom

time

V e l o c i t y P r o f i l e ( m / s )

Pipe bottom

Pipe top

Sonar array & Velocity Profile

Rev 10

Stop

flocculent

Pipe bottom

Pipe top

----- upstream

----- midstream

----- downstream

time


15/20

15






time


Pipe bottom

Pipe top


Rev 10

Stop

flocculent

Pipe bottom

Pipe top

----- upstream

----- midstream

----- downstream

time

Upstream Midstream Downstream


16/20

16






time


Pipe bottom

Pipe top


Rev 10

Stop

flocculent

Pipe bottom

Pipe top

----- upstream

----- midstream

----- downstream

time

Upstream Midstream Downstream


17/20

17

NO flocculant


Low-loss energy propagation

With flocculant

Newtonian flow

High-loss energy propagation

V o r t i c a l P o w e r Q u a l i t y

Pipe bottom

Pipe top

Sonar array & Vortical Power Quality

Rev 10

Stop

flocculent

----- upstream

----- midstream

----- downstream

time


18/20

up-stream mid-stream down-stream

Histograms, Vortical Power Quality

c o u n t

18

Vortical Power Quality (VPQ) changes with rheology

V

o r t i c a l P o w e r Q u

a l i t y

agglomerationLarge flocks in water-

based carrier fluid

water

mixer

Sonar

VPQSonar

VPQ

time

solids

MFT flocculantSonar

VPQ


19/20

Possible ImplementationMeasuring real-time rheology change with Sonar Array Flow Meter

19

Sonar

flow

meter

Sonar

flow

meter

Sonar

flowmeter

up-stream mid-stream down-stream

Histograms, Vortical Power Quality (VPQ)

c o u n t

VPQ VPQ VPQ


20/20

SummaryMeasuring rheology change with Sonar Array Flow Meter

20

• Agglomeration → Rheology change → Length scale change (particle size change)

• Length scale → Vortical Energy Transport (Kolmogorov Theory)

• Sonar array measures Vortical Energy Transport (power vs. wavenumber)

• Power vs. wavenumber “integrated” into Vortical Power Quality (standard measurement)

• rheology change → Change in Sonar Vortical Power Quality → real-time measurement

• Future work: move from “integrated” Vortical Power Quality figure of merit...to (better?)

spectrum measurement

Documents

S1_11_10_Robert_Maron_rev.pdf