Mechanistic Modeling and CFD Simulations of Oil-Water Dispersions in Separation Components TUSTP 2003 TUSTP 2003 by Carlos F. Torres May 20, 2003
Dec 28, 2015
Mechanistic Modeling and CFD Simulations of Oil-Water Dispersions
in Separation Components
Mechanistic Modeling and CFD Simulations of Oil-Water Dispersions
in Separation Components
TUSTP 2003TUSTP 2003TUSTP 2003TUSTP 2003
by
Carlos F. Torres
May 20, 2003
by
Carlos F. Torres
May 20, 2003
BackgroundBackground
Objectives Objectives
Particle Tracking ModelParticle Tracking Model
Preliminary Results Preliminary Results
Universal Dispersion ModelUniversal Dispersion Model
TopicsTopicsTopicsTopics
Knowledge of particle motion and phase distribution will Knowledge of particle motion and phase distribution will
enhance performance evaluation of separation equipmentenhance performance evaluation of separation equipment
TUSTP has used the Eulerian-Lagrangian technique to design TUSTP has used the Eulerian-Lagrangian technique to design
and analyze performance of separation devices such as and analyze performance of separation devices such as
GLCC, LLCC and LLHCGLCC, LLCC and LLHC
Existing models carry out simulations considering mainly the Existing models carry out simulations considering mainly the
following forces acting on a particle: drag and buoyancyfollowing forces acting on a particle: drag and buoyancy
Additionally, these models assume particle local equilibriumAdditionally, these models assume particle local equilibrium
BackgroundBackgroundBackgroundBackground
The general objectives of this study are to develop models The general objectives of this study are to develop models
capable of characterizing hydrodynamics of multiphase capable of characterizing hydrodynamics of multiphase
dispersion flow in separations and piping componentsdispersion flow in separations and piping components
Initially, study focuses on dilute and dense dispersed flow
Develop a mechanistic model for calculating droplet motion, Develop a mechanistic model for calculating droplet motion,
considering the different acting forcesconsidering the different acting forces
Determine dispersed phase void fraction
Validate and extend the three way coupling approach Validate and extend the three way coupling approach
proposed by Gomez 2001proposed by Gomez 2001
ObjectivesObjectivesObjectivesObjectives
General approachGeneral approach
Simplified approachSimplified approach
Future improvementsFuture improvements
Particle Tracking ModelParticle Tracking ModelParticle Tracking ModelParticle Tracking Model
Particle Tracking:Particle Tracking:General ApproachGeneral ApproachParticle Tracking:Particle Tracking:General ApproachGeneral Approach
Gomez 2001 presented a new Eulerian – Lagrangian Gomez 2001 presented a new Eulerian – Lagrangian
mechanistic model:mechanistic model:
Local equilibrium assumed for dispersed phaseLocal equilibrium assumed for dispersed phase
Forces used: drag, lift, body force, added mass and pressure Forces used: drag, lift, body force, added mass and pressure gradientgradient
Model is one way coupling between continuous and dispersed Model is one way coupling between continuous and dispersed phase, considering variation of interfacial areaphase, considering variation of interfacial area
Lagrangian EquationLagrangian EquationLagrangian EquationLagrangian Equation
0
otherpmbldp FFFFFF
dt
Vdm
Forces on particleForces on particle
Effects of continuous phase turbulence on particle:Effects of continuous phase turbulence on particle:
Behzadi et al (2001) presented an averaging approach for the Behzadi et al (2001) presented an averaging approach for the effects of fluid turbulence on particleseffects of fluid turbulence on particles
Iliopoulos et al. (2003) presented a stochastic model for the Iliopoulos et al. (2003) presented a stochastic model for the effects of turbulence in dispersed floweffects of turbulence in dispersed flow
Particle Tracking:Particle Tracking:Simplified ApproachSimplified ApproachParticle Tracking:Particle Tracking:
Simplified ApproachSimplified Approach Modifications of Gomez model (2001):Modifications of Gomez model (2001):
Forces considered: drag, lift and body forceForces considered: drag, lift and body force
Main goal is calculation of particle trajectoryMain goal is calculation of particle trajectory
Parametric technique (function of time) allows determination of Parametric technique (function of time) allows determination of particle’s residence time (integration 2particle’s residence time (integration 2ndnd order accuracy) order accuracy)
Particles are spherical and non-deformable, particle to particle Particles are spherical and non-deformable, particle to particle interaction not considered (dilute dispersion)interaction not considered (dilute dispersion)
One way couplingOne way coupling
3D solution developed for Cartesian and Cylindrical coordinate 3D solution developed for Cartesian and Cylindrical coordinate systemssystems
Modified Gomez Model Modified Gomez Model Modified Gomez Model Modified Gomez Model
Particle PositionParticle Position
bld FFF
0
1ti
ti
zii
1ti
ti
yii
1ti
ti
xii dtVzzdtVyydtVxx 111
Forces on ParticleForces on Particle
Particle Tracking:Particle Tracking:Future Improvements Future Improvements
Extend model capability to include:
Added mass force
Pressure gradient force (hydrodynamic)
Fluid turbulent effects
Particle transients effect
Develop mechanistic model for estimation of void fraction using stochastic approach
Explore limits of dilute flow assumption, and extend to dense flow
Preliminary ResultsPreliminary ResultsPreliminary ResultsPreliminary Results
Particle Tracking in Pipe FlowParticle Tracking in Pipe Flow
Particle Tracking in Stratified FlowParticle Tracking in Stratified Flow
Particle Tracking in Conventional SeparatorsParticle Tracking in Conventional Separators
Particle Tracking: Particle Tracking: Pipe FlowPipe Flow
Particle Tracking: Particle Tracking: Pipe FlowPipe Flow
Mixing Length Velocity ProfileMixing Length Velocity Profile
0 0.2 0.4 0.6 0.8 10
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Laufer, J. 1951, (Re = 40000)U+ Inner LayerU+ Outher Layer
Dimensionless Velocity Profile
U+/Umax+
y+/R
et
Re
y
maxUU
= 0= 0oo, d = 5in, V, d = 5in, Vcontcont = 0.01 m/s. = 0.01 m/s.
Water Continuous (1000 kg/mWater Continuous (1000 kg/m33, 1cp). , 1cp).
Dispersed phase Oil (850 kg/mDispersed phase Oil (850 kg/m33), dp = 100 microns), dp = 100 microns
Particle Tracking:Particle Tracking:Pipe FlowPipe Flow
Particle Tracking:Particle Tracking:Pipe FlowPipe Flow
Pipe length [m]
Pip
eh
eig
ht
[m]
0 0.5 1 1.5 2 2.5
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
With lift force. Residence time = 161.53 s
Without lift force. Residence time = 99.35 s
Shoham and Taitel (1984)Shoham and Taitel (1984)
= 0= 0oo, d = 3in, Uls = 0.1 m/s, Ugs = 1.0 m/s, d = 3in, Uls = 0.1 m/s, Ugs = 1.0 m/s
Air Water system at 25 Air Water system at 25 C and 1 atm. C and 1 atm.
Particle Tracking: Particle Tracking: Stratified FlowStratified Flow
Particle Tracking: Particle Tracking: Stratified FlowStratified Flow
X [m]
Y[m
]
-0.04 -0.02 0 0.02 0.04-0.04
-0.02
0
0.02
0.04 Vl [m/s]0.3500.3250.3000.2750.2500.2250.2000.1750.1500.1250.1000.0750.0500.0250.000
h/d = 0.5816
hl = 0.6035
Pipe length [m]
Pip
eh
eig
ht
[m]
0 1 2 3 4 5 6 7 8 9-0.04
-0.02
0
0.02
0.04
dp = 25 micros
dp = 50 micros
liquid level
1.2 kg/m3 1000 kg/m3
X [m]
Y[m
]
-1 -0.5 0 0.5 1 1.5 2 2.5 30
0.5
1
1.5
2
2.5
Velocity Magnitude2.600E+00
2.463E+00
2.326E+00
2.189E+00
2.053E+00
1.916E+00
1.779E+00
1.642E+00
1.505E+00
1.368E+00
1.232E+00
1.095E+00
9.579E-01
8.211E-01
6.842E-01
5.474E-01
4.105E-01
2.737E-01
1.368E-01
0.000E+00
Fluent 6.0
Oildensity = 850 kg/m3
viscosity = 30 cp
Velocityat the inlet = 2 m/sat the interphase = 0.2 m/s
Diameterat the inlet = 0.1 mat the outlet = 0.1 m
Vesselliquid level = 1 m
Reynolds Numberat the inlet = 5666.7in the vessel = 5666.7
Fluent 12 Mar 2003 title
x [m]
Y[m
]
0 0.5 1 1.5 2 2.5 3 3.5 40
0.5
1
1.5
2
2.5
Vel2.600E+00
2.463E+00
2.326E+00
2.189E+00
2.053E+00
1.916E+00
1.779E+00
1.642E+00
1.505E+00
1.368E+00
1.232E+00
1.095E+00
9.579E-01
8.211E-01
6.842E-01
5.474E-01
4.105E-01
2.737E-01
1.368E-01
0.000E+00
Vessel 2D v1.0
Oildensity = 850 kg/m3
viscosity = 30 cp
Velocityat the inlet = 2 m/sat the interphase = 0.2 m/s
Diameterat the inlet = 0.1 mat the outlet = 0.1 m
Vesselliquid level = 1 m
Reynolds Numberat the inlet = 5666.7in the vessel = 5666.7
Vessel 2D 12 Mar 2003 Vessel
Particle Tracking:Particle Tracking:Conventional SeparatorsConventional Separators
Particle Tracking:Particle Tracking:Conventional SeparatorsConventional Separators
x [m]
Y[m
]
0 0.5 1 1.5 2 2.5 3 3.5 40
0.5
1
1.5
2
2.5
Vel2.600E+00
2.463E+00
2.326E+00
2.189E+00
2.053E+00
1.916E+00
1.779E+00
1.642E+00
1.505E+00
1.368E+00
1.232E+00
1.095E+00
9.579E-01
8.211E-01
6.842E-01
5.474E-01
4.105E-01
2.737E-01
1.368E-01
0.000E+00
Vessel 2D v1.0
Oildensity = 850 kg/m3
viscosity = 30 cp
Velocityat the inlet = 2 m/sat the interphase = 0.2 m/s
Diameterat the inlet = 0.1 mat the outlet = 0.1 m
Vesselliquid level = 1 m
Reynolds Numberat the inlet = 5666.7in the vessel = 5666.7
Vessel 2D 12 Mar 2003 Vessel
X [m]
Y[m
]
-1 -0.5 0 0.5 1 1.5 2 2.5 30
0.5
1
1.5
2
2.5
Velocity Magnitude2.600E+00
2.463E+00
2.326E+00
2.189E+00
2.053E+00
1.916E+00
1.779E+00
1.642E+00
1.505E+00
1.368E+00
1.232E+00
1.095E+00
9.579E-01
8.211E-01
6.842E-01
5.474E-01
4.105E-01
2.737E-01
1.368E-01
0.000E+00
Fluent 6.0
Oildensity = 850 kg/m3
viscosity = 30 cp
Velocityat the inlet = 2 m/sat the interphase = 0.2 m/s
Diameterat the inlet = 0.1 mat the outlet = 0.1 m
Vesselliquid level = 1 m
Reynolds Numberat the inlet = 5666.7in the vessel = 5666.7
Fluent 12 Mar 2003 title
Particle Tracking:Particle Tracking:Conventional SeparatorsConventional Separators
Particle Tracking:Particle Tracking:Conventional SeparatorsConventional Separators
Particle Tracking: Particle Tracking: Conventional SeparatorsConventional Separators
Particle Tracking: Particle Tracking: Conventional SeparatorsConventional Separators
Particle Residence Time = 2.63 s
Particle Density = 2500 kg/m3
Particle Diameter = 500 micron
Particle Tracking: Particle Tracking: Conventional SeparatorsConventional Separators
Particle Tracking: Particle Tracking: Conventional SeparatorsConventional Separators
X
Y
0 1 2 3 40
0.5
1
1.5
2
2.5
Frame 001 12 Mar 2003 Particle Tracking
Particle Residence Time = 2.362 s
Particle Density = 2500 kg/m3
Particle Diameter = 500 micron
Universal Dispersion ModelUniversal Dispersion Model
Gomez Model (2001)Gomez Model (2001)
The Eulerian field is known (average velocities, turbulent kinetic The Eulerian field is known (average velocities, turbulent kinetic energy and energy dissipation)energy and energy dissipation)
Solve Lagrangian field using the proposed equation, to calculate Solve Lagrangian field using the proposed equation, to calculate slip velocity within flow fieldslip velocity within flow field
Solve diffusion equation using slip velocity information, to Solve diffusion equation using slip velocity information, to predict void fraction distributionpredict void fraction distribution
Calculate bubble or droplet diameter using Eulerian turbulent Calculate bubble or droplet diameter using Eulerian turbulent quantities and void fraction distributionquantities and void fraction distribution
Repeat non-linear process until convergence is reachedRepeat non-linear process until convergence is reached
Phase Coupling Model Phase Coupling Model
Definition of Phase Coupling
One-way Coupling: Fluid flow affects particle while there is no reverse effect.
Two-way Coupling: fluid flow affects particle and vice versa.
Four-way Coupling: Additionally from above, there are hydrodynamic interactions between particles, and turbulent particle collisions.
Three-way CouplingThree-way Coupling
Phase Coupling ModelPhase Coupling Model
iiiji
j
j
i
jij
iji sisouux
u
x
u
xx
P
x
uu
t
uTMP
1
Dispersed phase momentum equation (average)Dispersed phase momentum equation (average)
Continuous phase momentum equation (N- S Equation) Continuous phase momentum equation (N- S Equation)
otherturbulencepmbldp
p FFFFFFFdt
Vdm
Particle Source Term, MPParticle Source Term, MPsoso is estimated by coupling mass and is estimated by coupling mass and momentum balances over control volume. momentum balances over control volume.
Two-way Coupling: Two-way Coupling: Solution SchemeSolution Scheme
PSI – Cell technique, Crowe et al. (1977) PSI – Cell technique, Crowe et al. (1977)
Huber &Huber &Sommerfelt (1997).Sommerfelt (1997).
Air continuousAir continuousPhase. Phase. = 0= 0oo, d = 80 mm,, d = 80 mm, V = 24 m/s, V = 24 m/s,
Dispersed phaseDispersed phasedd = 2500 kg/m = 2500 kg/m33
ddpp = 40 micron = 40 micron
Model PotentialModel Potential
LLCCDispersion of Oil in Water
with Water Layer at the BottomVm = 0.6 m/s W.C = 67%
QuestionsQuestions
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