Modeling of Underwater Liquid Releases, Slick Transport

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Modeling of Underwater Liquid Releases, Slick
Transport Evaporation

• V.M. Fthenakis and U.S. Rohatgi
• Department of Advanced Technology
• Brookhaven National Laboratory

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Discharge Model
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APG Spill from a Barge in Mississipi River -Baton
Rouge, Louisiana
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Overview

• Consequence analysis requires modeling of
  1) discharge, 2) transport in water, 3)
  evaporation and 4) atmospheric dispersion
• Previous discharge models limited to initial
  hydrostatic pressure difference (Dodge, 1980
  Fannelop, 1994) . A new discharge model was
  developed
• Oil slick transport in rivers (Shen Yapa, 1988)
• Multicomponent evaporation ( PAVE)
• Atmospheric Dispersion (ALOHA, ISC)

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Modeling

• Discharge Model
• Phase 1- Initial hydrostatic pressure difference
• Phase 2- Periodic vessel movements
• Verification Sensitivity Analysis
• Spreading Evaporation Model
• Application to Real Incident
• Atmospheric Dispersion Modeling
• Verification of Predicted Concentrations

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Discharge Model
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Discharge Due to Oscillations
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Discharge Due to Oscillations
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Discharge Due to Oscillations
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Discharge Model

• Assumptions
• Isothermal Outflow and/or Inflow
• Incompressible, Immiscible fluids
• Ideal gas expansion in the vessels void space
• Based on analytical solutions for non-vented and
  vented vessels discharges due to hydrostatic
  pressure and periodic oscillations from waves
  and bouncing
• The model predicts
• Water inflows / fluid-and-water outflows with
  time
• Change of void space and fluid inventory with
  time
• Change of water level in the barge with time
• Critical water layer thickness and inventory in
  steady-state

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Discharge Model -Phase 1 Verification

• Experimental data (Dodge et al., 1980)

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Discharge Model- Sensitivity Analysis

• Gas-phase pressure
• Temperature Saturation Pressure
• Depth of the break
• Area of the break
• Discharge coefficient
• Fluid density
• Amplitude of vessel movement
• Period of vessel movement

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River Spreading Modeling

• Advection of the slick due to river currents and
  the wind
• Spreading of the slick due to gravitational,
  inertia, viscous and surface tension forces
• Multi-component evaporation

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Spreading Evaporation Model
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Evaporation Modeling

• Experimental studies -(crude oil, Payne et al.
  1984 chlorobenzene and toluene, Waden and
  Triemer, 1989)
• PAVE multi-component evaporation model
• Diffusion through the liquid phase and mass
  transfer from surface.
• Heat conduction to water, convection to the
  atmosphere, solar radiation, atmospheric
  radiation and evaporative cooling
• Verified with chlorobenzene and toluene
  evaporation data

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Break Flow Evaporation Rates
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Spill Area as function of Time
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Spill Area after 10 Minutes
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Spill Area after 20 Minutes
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Spill Area after 30 Minutes
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Spill Area after 45 Minutes(Leak lasted 30
minutes)
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Spill Area after 75 Minutes
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Spill Area after 100 Minutes
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A Barge Discharge Incident

• A barge-tank containing APG overturned in the
  Mississippi River in March 1997
• For days the barge was bounced by tugboats
  moved by river currents leaking APG from valves
  under the water
• Buoyant APG fluid floated to the surface
• Barge was loaded with 400,000 gal of APG and
  lost at least 15 of it during the incident
• The incident lasted 11 days till barge was upheld
  and remaining APG recovered

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Barge Incident Predictions of Release Rates
during 11 Days
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Fluid Left in the Barge ()
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Baton Rouge -APG Spill in MississipiALOHA
predictions on MARPLOT map
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Cumulative APG Dose (ppm-hr) 11 days -ISC3
predictions
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Conclusion

• New model of underwater liquid leaks from vessel
  in periodic motion.
• New model of spreading of a river spill.
• Limited verification and sensitivity analysis
  showed that predictions are reasonable.
• The models were applied to a known incident and
  the predictions were in agreement with
  observations and measurements.
• These models may be used in real time to minimize
  consequences of accidental releases.