Modelling of Dispersion from Direct Injection of Carbon Dioxide in the Water Column

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Modelling of Dispersion from Direct Injection of
Carbon Dioxide in the Water Column
Baixin Chen and Makoto Akai National Institute of
Advanced Industrial Science and Technology
(AIST), Japan
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• Turbulent Multiphase Mixing and Interactions
  (Mass, Momentum,Energy Exchanging and Phase
  Changing)
• Droplet- seawater interactions drag,
  deformation, raising
• Droplets interaction (collision, coalescence,
  second breakup)
• CO2 dissolution or shrinking
• CO2 hydrate dynamics gasification
• Local turbulent flow, wake, and mixing
• Chemical reactions of dissolved CO2 and seawater
• Biological Impacts

What must be handled!
Ocean Surface
Mesoscale Eddies

• Small-scale ocean turbulence and turbulent wakes
• Two-fluid modeling
• Biological Impact Modeling

2000m
CO2
CO2 injection Droplets formation
HydrateDistributions of Initial Diameter and
Number Density Towering pipe wakes..
Ocean Currents
1001000 m
10 100 Km Horizontal 2-D modeling of CO2
dispersion
Bottom Boundary Layer
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Models developed

• Alendal et al. (NERSC Technical Report,1998
  JGR-ocean, 2002)
• Sato et al. (RITE report, 1998ASME,2000 GHGT-6,
  2002)
• Chen et al.(RITE report, 1999 ASME,2000 Tellus,
  2003)

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Outline

• Introduction of the model developed
• Case investigation
• Release of CO2 from fixed port
• Release of CO2 from a towered
  pipe
• Conclusions

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A Near-field Physical biological impact model
of CO2 Ocean Sequestration
1. Modeling of Small scale ocean turbulent flow
(Re-construction)
2. Modeling of momentum and mass transfer between
CO2 droplets and seawater
3. Modeling of biological impacts of
floating-orgms.
Sub-model of CO2 droplet drag coefficient

• Conservative variables
• Mass or Number density of organism k

Forced-dissipative ocean turbulent flow model
Sub-model of CO2 droplet deformation

• Non-conservative variables
• Degree of Damage/Activity Index, Ak.

CO2 enrich-seawater dynamic model
Sub-model of CO2 solubility
Sub-models of Damage Degree /Activity Index
Supported by Lab. and field Exp.
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Part I Reconstruction of small scale
turbulent ocean with basis on observation data

• Theories and physical model
• Observation data analysis and
• implement

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Turbulent kinetic energy spectrum in the ocean
(J. D. Wood in Nature 1985 and CREIPI at
Keahole Pt. Offing,1999)
Eddy resolving truncation scale (10 km) by Earth
Simulator (0.1deg.) in Japan
Horizontal
Eddy resolving truncation scale (1 m) by
Small-scale two-phase model
Vertical
Meso-scale ocean model
Small-scale two-phase model
N-S B-230m
Frequency (CPs)
CREIPI at Keahole Pt. Offing,1999
Eddy resolving truncation scale (100km) by year
2000 estimated by Wood in 1985
Forced-dissipative and kinetic energy cascade
theories applied?
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Theories and Techniques Applied

• Inside of the ocean
• N-S based 3-D unsteady Governing Eq.s
• Forced-dissipative Energy cascade theories
• Adjusted by observation spectrum

• Large-scale information from Boundaries
• Mean properties (X,t)
• Turbulent properties
• at K gt Kf

Data analysis
Field Obs. Data
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Governing Equations for simulating small-scale
ocean turbulence
a. Forced-dissipative system of small-scale
ocean
Forced term
Dissipative term
b. Structure
-
function Turbulent viscosity model
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1-4. Example Hawaiian Case (small-scale)
Computational domain, initial boundary conditions
output
X2 300m N2 128
X3 300 m N3128 Periodic conditions
?0 f(T0,S0)
Inlet
solid wall
X1 500 m N1 256
U1m(x3), T0(x3) S0 (x3)are the observation data
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Simulations of small-scale ocean turbulence
Instantaneous velocities and temperature T
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Part-II CO2 droplet dynamicsExperimental
Observations and Modeling Assumptions

• AssumptionCO2 droplet with hydrate covered is a
  Deformable rigid droplet with Permeable Surface
• Experimental data adopted are those from
  Stewart(1970) and Kimuro (1994) for CO2
  solubility, and from Ohgaki (1993) for phase
  diagram.
• Experiment data dealing with momentum transfer
  between droplets and seawater are from the
  experiments of Dr. Ozaki (1999)

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Sub-models of drag coefficient and terminal
velocities
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Key Parameters Cd Drag coefficient Sh Sherwood
Number Cs The solubility a The effective area
coefficient
Model prediction of an individual droplet
dissolution (model calibration) (CO2 droplet
Diameter vs Exp data by P. Brewer et al)
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CO2 droplet dissolution at variant depth
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Ascending /Descending of CO2 droplet
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Two-fluid ocean turbulent flow model
Governing Equations of LCO2
Governing Equations of Seawater
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Density change of CO2 enriched seawater
?s ?w (1.0 ?? ) ?s CO2 solution density
?w seawater density ? CO2 mass fraction
?0.273 by Exp (Song et al. 2003)
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Part III Dispersion from Direct Injection of
Carbon Dioxide in the Water Column

• Injection of CO2 from fixed ports

• Injection of CO2 from towered pipe

/sec
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Dispersion from a fixed port release
CO2 droplet plume
CO2 enriched water plume
T32 min
T32 min
T93 min
T93 min
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Plume characters from a fixed port
T93 min
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Lower Injection rate (pH plume at middle depth)

Mc0.6kg/s D0 8.0mm
Mc0.1kg/s D0 8.0mm
T100.3 min
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Dispersion from a towered pipe release
X10 m
X180 m
T23 min
T1.0 min
T70 min
T70 min
Yc0.01kg m-3
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Statistical characteristics of CO2 enriched
seawater plume
Fixed ports
Towered pipe
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Statistical characteristics of CO2 enriched
seawater plume
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Conclusions

• Near-filed physical and chemical process created
  by directly injected LCO2 into the ocean waters
  could be reasonably simulated.
• To engineering application, injection of LCO2
  from fixed ports should be carefully arranged to
  limit the local injection rate associated with
  the selection of an incline seafloor.
• In case of large injection rate (100kg/s) from
  fixed port on a flat seafloor, injected LCO2
  could yield a large pH change and an unsteady
  waving double-plume.
• Alternatively, release of LCO2 from a towered
  pipe at middle-depth with a relatively large size
  droplets is an expectable option to practically
  performance of CO2 ocean sequestration, which
  could be adjusted with the limitation of
  biological impact.
• Understanding of the effect of dissolved CO2 on
  oceanic bio-organisms appeared to be urgently
  necessary for assessing the oceanic environmental
  impacts.
• . We still have
  more works to be done .

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Acknowledgements

• This study is a part of the investigation of
  two projects A research Project on Accounting
  Rules on CO2 Sequestration for National GHG
  Inventories (ARCS) managed by National Institute
  of Advanced Industrial Science and Technology
  (AIST) and The CO2 Ocean Sequestration Project
  managed by Research Institute of Innovative
  Technology for the Earth (RITE). New Energy and
  Industrial Technology Development Organization
  (NEDO), Japan, fund both projects.