modeling of underwater liquid releases, slick transport & evaporation

Modeling of Underwater Liquid Releases, Slick Transport & Evaporation

V.M. Fthenakis and U.S. Rohatgi

Department of Advanced Technology

Brookhaven National Laboratory

International Conference and Workshop on Modeling the Consequences ofAccidental Releases of Hazardous Materials, San Francisco, CA, Sept. 27-30, 1999

Discharge Model

VAPOR

FLUID

WATER

River Current

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

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

OverviewOverview

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)

Modeling 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

Discharge Model .

VAPOR

FLUID

Inflow WATERof WATER

River Current

Outflow

Discharge Due to OscillationsDischarge Due to Oscillations

VAPOR

FLUID WATER

WATERWaterInflow

River Current

Discharge Due to OscillationsDischarge Due to Oscillations

VAPOR

FLUID WATER

Outflow

WATER

River Current

Discharge Due to OscillationsDischarge Due to Oscillations

VAPOR

FLUID WATER

WATERWaterInflow

River Current

Discharge ModelDischarge Model Assumptions: Isothermal Outflow and/or Inflow Incompressible, Immiscible fluids; Ideal gas expansion in the vessel’s 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

Discharge Model -Phase 1 VerificationDischarge Model -Phase 1 Verification

Experimental data (Dodge et al., 1980)

Liquid Density(kg/m3)

Psat(atm)

Discharge (%)Experiment Model

Iso-propylAlcohol

783 0. 2.0 2.5

MethylChloride

1280 0.92 97.6 97.7

Iso-pentane 599 0.92 97.6 100.

Discharge Model- Sensitivity AnalysisDischarge 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

River Spreading Modeling 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

Spreading & Evaporation ModelSpreading & Evaporation Model

Change of spill thickness, width, leading edge andtrailing edge as a function of time

Spill volume decreasing due to evaporation

)48(

0 0

hXdydxdt

Xhd LEX h

LELE

Evaporation ModelingEvaporation 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

Break Flow & Evaporation RatesBreak Flow & Evaporation Rates

0 20 40 60 80 100 120 140 160 180 200

TIME (min)

0

2

4

6

8

10

12

14

16

18

Ev

ap

/Bre

ak

Flo

w r

ate

(k

g/s

)

Evaporation Rate, Ka=2.e-7

Break Flow Rate

Evaporation Rate, Ka=1.e-7

Spill Area as function of TimeSpill Area as function of Time

0 20 40 60 80 100 120 140 160 180 200

TIME (min)

0100002000030000400005000060000700008000090000

Sp

ill A

rea

(m

2) Ka=2.e-7

Ka=1.e-7

Spill Area after 10 MinutesSpill Area after 10 Minutes

0 1000 2000 3000 4000 5000 6000

Location From Barge (m)

-40

-30

-20

-10

0

10

20

30

40

Plu

me

wid

th (

m)

10 min

Spill Area after 20 MinutesSpill Area after 20 Minutes

0 1000 2000 3000 4000 5000 6000

Location From Barge (m)

-40

-30

-20

-10

0

10

20

30

40

Plu

me

wid

th (

m)

10 min

20 min

Spill Area after 30 MinutesSpill Area after 30 Minutes

0 1000 2000 3000 4000 5000 6000

Location From Barge (m)

-40

-30

-20

-10

0

10

20

30

40

Plu

me

wid

th (

m)

10 min

20 min

30 min

Spill Area after 45 Minutes(Leak lasted 30 minutes)

Spill Area after 45 Minutes(Leak lasted 30 minutes)

1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Location from Barge, m

40

30

20

10

0

-10

-20

-30

-40

Plu

me

wid

th, m

45 min

Spill Area after 75 MinutesSpill Area after 75 Minutes

1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Location from Barge, m

40

30

20

10

0

-10

-20

-30

-40

Plu

me

wid

th, m

75 min

Spill Area after 100 MinutesSpill Area after 100 Minutes

1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Location from Barge, m

40

30

20

10

0

-10

-20

-30

-40

Plu

me

wid

th, m

100 min

A Barge Discharge IncidentA 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

Barge Incident: Predictions of Release Rates during 11 Days

Barge Incident: Predictions of Release Rates during 11 Days

1

10

100

1,000

10,000

100,000

0 24 48 72 96 120 144 168 192 216 240 264Time (hours from start of incident)

AP

G D

isch

arge

(kg/

hr)

Fluid Left in the Barge (%)Fluid Left in the Barge (%)

84

86

88

90

92

94

96

98

100

0 24 48 72 96 120 144 168 192 216 240 264

Time (hr)

% A

PG

le

ft i

n b

arg

e

Baton Rouge -APG Spill in MississipiALOHA predictions on MARPLOT map

Baton Rouge -APG Spill in MississipiALOHA predictions on MARPLOT map

Cumulative APG Dose (ppm-hr) 11 days -ISC3 predictions

Cumulative APG Dose (ppm-hr) 11 days -ISC3 predictions

P er io d av erag e c oncentra tions ppm -h r

665200 670200 675200 6802003356700.00

3361700.00

3366700.00

3371700.00

3376700.00

3381700.00

3386700.00

3391700.00

5

10

30

50

100

750

1000

1500

2000

3000

ConclusionConclusion

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.