Simulation of Solvent Simulation of Solvent

Extraction Processes in Extraction Processes in

Annular Centrifugal Annular Centrifugal

ContactorsContactors

Kent E. Wardle, Kurt Frey, Brian Gullekson

(student), and Candido Pereira

Chemical Sciences and Engineering Division

Argonne National Laboratory

NEAMS Fall 2010 PI Meeting

19 October 2010

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 2

Simulations of Solvent Extraction Processes in Annular Centrifugal Contactors

FY10 Work

� Molecular-scale

– Development and testing of

polarizable intermolecular potential

for key extractant in fuel recycling

(TBP), preliminary liq-liq MD

� Continuum-scale

– Demonstration of multiphase Finite

Element-based (unstructured) Lattice

Boltzmann Method (FELBM) for

annular mixer geometry

– Equipment-scale simulations of 3-

phase liquid-liquid-air flow in annular

centrifugal contactor using

OpenFOAM

Provide computational tools for detailed simulation of unit operations with the aim of

Goal:Goal: providing a pathway for prediction of stage efficiency for given conditions and a means

of developing lower fidelity models for plant-level unit operations

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 3

Simulations of Solvent Extraction Processes in Annular Centrifugal Contactors

FY10 Work

� Molecular-scale

– Development and testing of

polarizable intermolecular potential

for key extractant in fuel recycling

(TBP), preliminary liq-liq MD

� Continuum-scale

– Demonstration of multiphase Finite

Element-based (unstructured) Lattice

Boltzmann Method (FELBM) for

annular mixer geometry

–– EquipmentEquipment--scale simulations of 3scale simulations of 3--

phase liquidphase liquid--liquidliquid--air flow in air flow in

annular centrifugal contactor using annular centrifugal contactor using

OpenFOAMOpenFOAM

Provide computational tools for detailed simulation of unit operations with the aim of

Goal:Goal: providing a pathway for prediction of stage efficiency for given conditions and a means

of developing lower fidelity models for plant-level unit operations

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 4

Molecular-scale

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 5

Predictive Molecular Dynamics (MD) using Polarizable Intermolecular Potentials

� Built a polarizable model of tributyl phosphate

(TBP) based on Drude particle method

– Massless particles with charge tethered to

atomic sites that move in response to fields

� Comparison of property predictions versus

‘standard’ model and experimental values

– Polarizable model gives excellent results ↓� Performed preliminary simulations using non-

polarizable models for water/TBP/dodecane

system as a baseline for future comparison ↗

5.6%8.541.29%3.14 ± 0.51-1.75%2.25 ±0.01

2.16%3.731 ±0.078

Polarizable

45.2%11.7555.5%4.82 ± 1.23-10.5%2.05 ±0.03

4.43%3.814 ±0.020

Non-

Polarizable

%Error

(8.09)

Dielectric

Const

%Error

(3.1)

Dipole

Moment, D

%Error

(2.29)

Diff.

Const.1,

106 cm2/s

%Error

(3.652)

Density,

mol/LModel

1 Diffusion constant was calculated from only a single time reference rather than an average over many reference times.

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 7

Continuum-scale

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 8

Our “Reactor(s)”

Solvent Extraction Equipment

� Packed Columns

� Pulsed Columns

� Mixer Settlers

� Centrifugal Contactors

– Small size

• Physical footprint

• Nuclear criticality

– Short residence time

• Low process hold-up

• Less solvent degradation

– High extraction efficiency

– High throughput

– Quick start-up/shut-down

• Maintain conc. profile

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 9

Continuum-scale

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 10

Scale-bridging Simulations using Unstructured Finite Element-based Lattice Boltzmann Method (FELBM)

� Finite Element-based Lattice Boltzmann

Method (FELBM)

– Scales well to thousands of processors, requires

only nearest neighbor info w/ no global

pressure solve

– Free-energy based method for multiphase with

dynamic contact angle

� Challenges

– LBM has better parallel scaling than traditional

CFD, but larger memory needs

– Stability can be an issue for multiphase

simulations in turbulent regime

– Not fully incompressible

� Applications

– Multiphase flow in annular mixing geometry →– Future work could focus on application to high

resolution DNS-like simulations of droplet

dynamics Vorticity magnitude of Taylor-Couette flow with a

free surface in annular mixer (radius ratio = 0.833)

Collaboration with Taehun Lee of City College of New York

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 11

Centrifugal Contactor Simulations UsingOpen-Source CFD

OpenFOAM® (www.openfoam.com)

– Open-source toolkit - collection of libraries and solvers

– Capable of wide variety of physics

• Multiphase, turbulent, moving boundary, etc.

– Good parallel performance

• >2-4 times faster than comparable commercial CFD

• Scales down to ~5K polyhedral cells/processor (Linux cluster)

Free surface flow examples (water/air):

← flow in mixing zone

flow in the upper section of the rotor ↑flow in coupled mixing/separation zone model ↗

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 12

Three-phase Water-Oil-Air Annular Mixing Simulation Using Open-source CFD (OpenFOAM)

� Only ‘large’ droplets are resolved (~1mm)

– Actual droplet size, ~25 µm

– ~5 µm mesh (Δx, ~50x smaller)

• N ~ 1×1011 cells

• Δt ~ 1×10-7 s

• Cr limit, as Δx ↓, Δt ↓

25.0≈∆

∆=

x

tuCr

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 13

Video of Liquid-Liquid Mixing

water is transparent

blue

oil is red

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 14

Three-phase Simulations of Coupled Mixing/Separation Zone Model

Time evolution of total liquid volume for each phase in the two regions: mixing separation

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 15

New Multiphase Models are Needed

� Euler-Euler-VOF Coupled Multiphase Model

– VOF (interface capturing/tracking) to capture liquid-air interface and fluid/rotor interaction

– Compatible multiphase model for unresolved scales of liquid-liquid dispersion

• Sub-grid models for droplet breakup/coalescence and mass/momentum transfer ← LANL

� Combination not available in existing commercial codes (except ANSYS-CFX)

� Proposed progression of methods to be implemented in OpenFOAM VOF solver

– Euler-Euler with fixed dispersed phase droplet size and characteristic drag model (as in

Padial-Collins et al. 2006)

– Population Balance Equation (PBE) using DQMOM (as in Silva et al. 2008 – in OpenFOAM)

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 16

Experimental

observations

Interface with Experimental Work

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 17

Contactor CFD Validation Using Electrical Resistance Tomography (ERT)

Contactor ERT (CERT) Facility

� Engineering-scale contactor (CINC V-5)

� Multiphase measurements using ERT

� Detailed operational diagnostics

electrodes

‘reconstructed’

phase fraction

maps ↘

Kent E. Wardle – CSE

current in

current out

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 18

Summary and Path Forward

Summary of FY10 WorkSummary of FY10 Work

� Molecular-scale

– Polarizable intermolecular potential for TBP and prelim liq-liq MD →

� Continuum-scale

FY11 WorkFY11 Work

�Develop Euler-Euler multiphase solver for OpenFOAM that can incorporate mass and

momentum transfer terms (from LANL team) for simulation of liquid-liquid mixing and

extraction in the centrifugal contactors

�Work with FMM on supporting elements (?)

–Predictive liquid-liquid MD using polarizable intermolecular potentials

–Application of FELBM to high resolution ‘DNS-like’ simulations of droplet dynamics

–Multiphase Finite Element-based (unstructured) Lattice

Boltzmann Method (FELBM) for annular mixer ←

–Equipment-scale liquid-liquid-air simulations in annular

centrifugal contactor using OpenFOAM →

K. Wardle – Liq-liq Contactor CFD – NEAMS PI Meeting 2010 19

Acknowledgements

� Ralph Leonard, Chemical Sciences and Engineering Division, Argonne

� Taehun Lee, Mechanical Engineering Dept. City College of New York

This work was supported by the U.S. Department of Energy, Office of Nuclear

Energy, under Contract DE-AC02-06CH11357.

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