United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
EPA-600/2-78-128
June 1978
Research and Developmant
Techniques for
Mixing Dispersants
with Spilled Oil
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2 Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8 "Special' Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical informa-
tion Service. Springfield, Virginia 22161.
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EPA-600/2-78-128
June 1978
TECHNIQUES FOR MIXING DISPERSANTS WITH SPILLED OIL
by
Gary F. Smith
Mason & Hanger-Silas Mason Co., Inc.
Leonardo, New Jersey 07737
Contract No. 68-03-0490
Project Officers
Frank J. Freestone
John S. Farlow
Oil and Hazardous Materials Spills Branch
Industrial Environmental Research Laboratory
Edison, New Jersey 08817
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
-------
DISCLAIMER
This report has been reviewed by the Industrial Environmental
Research Laboratory, U.S. Environmental Protection Agency, and approved
for publication. Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental Protection
Agency, nor does mention of trade names or commercial products constitute
endorsement or recommendation for use, nor does the failure to mention
or test other commercial products indicate that other commercial products
are not available or cannot perform similarly well as those mentioned.
ii
-------
FOREWORD
When energy and material resources are extracted, processed, con-
verted, and used, the related pollutional impacts on our environment and
even on our health often require that new and increasingly more effi-
cient pollution control methods be used. The Industrial Environmental
Research Laboratory -Cincinnati (lERL-Ci) assists in developing and
demonstrating new and improved methodologies that will meet these needs
both efficiently and economically.
This report describes performance testing of three standard devices
and one experimental device for mixing dispersants with spilled oil.
Based on these results, a user can select the method best suited to his
operating conditions. The methods, results, and techniques described
are of interest to those interested in specifying, using, or testing
such equipment. Further information may be obtained through the Resource
Extraction & Handling Division, Oil and Hazardous Materials Spills
Branch, Edison, New Jersey.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
iii
-------
ABSTRACT
The effective use of some oil spill dispersants requires the addition
of mixing energy to the dispersant-treated slick. Various methods of
energy application have included the use of fire hose streams directed
to the water surface, outboard motors mounted on work boats, and the
five-bar gate, a pallet-like device towed on the surface behind vessels
of opportunity.
The U.S. Environmental Protection Agency sponsored this test pro-
gram at their Oil and Hazardous Materials Simulated Environmental Test
Tank (OHMSETT) to evaluate the above devices as well as a modified
version of the five-bar gate. Three test fluid mixtures with different
interfacial tensions were distributed onto the water surface, and each
mixing device was towed through them at speeds from 1.02 m/s to 2.54 m/s
in three wave conditions. Droplet penetration was documented via under-
water photography.
Analysis of the results showed that the modified five-bar gate
produced the greatest overall penetration (2.4 m) at a tow speed of 2.0
m/s. In general, performance was unaffected by wave action, and vari-
ations in interfacial tension produced no observable trend among all
devices.
This report was submitted in fulfillment of Contract No. 68-03-
0490, Job Order No. 24, by Mason & Hanger-Silas Mason Co., Inc., under
the sponsorship of the U.S. Environmental Protection Agency. This
report covers the period April 22 to May 6, 1976, and work was completed
as of January 1, 1977.
iv
-------
CONTENTS
Foreword iii
Abstract iv
Figures vi
Tables vi
Abbreviations and Symbols vii
List of Conversions viii
Acknowledgment ix
1. Introduction ..... 1
2. Conclusions 3
3. Recommendations • 5
4. Materials and Methods 6
5. Experimental Procedures 12
6. Results and Discussion 14
References ........ 17
Appendices
A. OHMSETT Description 18
B. Test Procedures 20
C. Test Results 24
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FIGURES
Number Page
1 Photograph of fire hose nozzles 7
2 Photograph of motorboat 7
3 Diagram of five-bar gate 8
4 Photograph of standard five-bar gate 9
5 Photograph of modified five-bar gate 9
6 Modified five-bar gate 10
7 Facility modifications 11
TABLES
1 Test Fluid Properties .... 1
2 Primary Test Matrix 13
3 Maximum Droplet Penetration for Different Interfacial
Tensions in Calm Water 14
4 Maximum Droplet Penetration for Different Wave
Conditions 15
vi
-------
ABBREVIATIONS
ABBREVIATIONS AND SYMBOLS
cm
CPM
dynes/cm
ergs/cm2
HC
HLB
IFT
JO 24
J/m2
kg
KJ/m
kw
m
m/s
mm
mV
N/m
OHMSETT
ppt
sin
Whit.
K.E.
-centimetre
-crests per minute
-dynes per centimetre
-ergs per centimetre squared
-harbor chop wave condition
-hydrophilic to lipophilic balance ratio
-interfacial tension
-job order 24
-joules per metre squared
-kilograms
-kilojoules
-kilowatt
-metres
-metres per second
-millimetre
-millivolts
-newton per metre
-Oil and Hazardous Materials Simulated Environmental
Test Tank
-parts per thousand
-sine
-Whitman
-Kinetic energy
SYMBOLS
L
o
ro/w
%
So/w
ro
rw
-angular degrees
-degrees
-interfacial tension of oil/water
-percent
-spreading coefficient for oil on water
-surface tension of oil
-surface tension of water
vii
-------
CONVERSIONS
METRIC TO ENGLISH
To convert from
Celsius
joule
joule
kilogram
metre
metre
metre2
metre2
metre3
metre3
metre/second
metre/second
metre2/second
metre3/second
metre3/second
newton
watt
ENGLISH TO METRIC
centistoke
degree Fahrenheit
erg
foot
foot2
foot/minute
foot3/minute
foot-pound-force
gallon (U.S. liquid)
gallon (U.S. liquid)/
minute
horsepower (550 ft
Ibf/s)
inch
inch2
knot (international)
litre
pound-force (Ibf avoir)
pound-mass (Ibm avoir)
to
degree Fahrenheit
erg
foot-pound-force
pound-mass (Ibm avoir)
foot
inch
foot2
inch2
gallon (U.S. liquid)
litre
foot/minute
knot
centistoke
foot3/minute
gallon (U.S. liquid)/minute
pound-force (Ibf avoir)
horsepower (550 ft Ibf/s)
metre2/second
Celsius
joule
metre
metre2
metre/second
metre3/second
joule
metre3
metre3/second
watt
metre
metre2
metre/second
metre3
newton
kilogram
viii
Multiply by
1.000
7.374
2.205
3.281
937
076
549
642
000
969
944
000
2.119
587
248
1.341
(tF-32)/1.8
E+07
E-01
E+00
E+00
E+01
E+01
E+03
E+02
E+03
E+02
E+00
E+06
E+03
E+04
E-01
E-03
1.000 E-06
tc = (tF-32)/1.8
1.000 E-07
3.048 E-01
9.290 E-02
5.080 E-03
4.719 E-04
1.356 E+00
3.785 E-03
6.309 E-05
7.457 E+02
2.540 E-02
6.452 E-04
5.144 E-01
1.000 E-03
4.448 E+00
4.535 E-01
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ACKNOWLEDGMENTS
U.S. Environmental Protection Agency project representative, Mr.
Leo McCarthy, provided valuable guidance and contributed significantly
to the success of this project.
Mr. S.G. Keadle of Mason & Hanger contributed significantly to the
design and fabrication of the modified five-bar gate.
ix
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SECTION 1
INTRODUCTION
BACKGROUND
Some dispersants require the addition of mixing energy after their
application to the oil slick. Much research effort has been applied to
the development of dispersant chemicals, methods of application to oil
slicks, and the effects of dispersant use on marine life (references 2
through 7). However, relatively little effort has been expended on
developing effective devices to stir the oil/dispersant mixture into the
water column (8). Devices used thus far include water streams from fire
hoses, motorboat propeller wash, and the five-bar gate developed by the
Warren Springs Laboratory (8). The performance of "these dispersant
mixing devices, when applied to floating oil slicks in the OHMSETT test
tank (see Appendix A), is qualitatively evaluated in this report.
SCOPE
The purpose of this project was to test and evaluate oil spill/-
dispersant mixing equipment. The equipment tested consisted of a motorboat,
a fire hose system, a standard five-bar gate, and a specially modified
five-bar gate. Test conditions and procedures were designed to simulate
typical real world environments and to permit a performance evaluation
of the equipment when used on oil. The oil selected for the tests was
Sunvis #31, used as delivered (no surfactant added), and two mixtures of
oil and surfactant (Igepal CO-430). Properties of these three test
mixtures are given in Table 1.
TABLE 1. TEST FLUID PROPERTIES
Test fluid
Sunvis #31
Viscosity
(xl(T6m2/s)
190
Interfacial
tension
(xlO~3N/m)
18
Surface
tension
(xlO"3N/m)
31
Specific
Gravity
0.868
Sunvis #31
plus ^ 0.025%
Igepal CO-430 220
Sunvis #31
plus ^ 0.05%
Igepal CO-430 235
29
29
0.868
0.868
-------
Spreading rate near the source of an oil slick is based on the
volume and density of the oil. This provides a static head which over-
comes other factors such as surface tension and oil viscosity, and
causes the oil to spread across the water surface. Spreading rate and
thickness of the oil film varies with time and distance from the origin,
with surface tension and viscosity forces eventually dominating.
Canevari (2) finds the spreading to be predicted by a spreading
coefficient. The coefficient is defined as:
so/w = rw ~ ro/w - ro
where So/w = spreading coefficient for oil on water,
ergs/cm
rw = surface tension of the water phase, dynes/cm
ro = surface tension of the oil phase, dynes/cm
ro/w = interfacial tension of the oil/water phase, dynes/ci
:m
If So/w is a positive value, the oil will spread on water; other-
wise, it will not.
It can be seen from the equation above that lowering the inter-
facial tension between oil and water will increase the spreading co-
efficient. Each surfactant molecule contains both water compatible
(hydrophilic) and oil compatible (lipophilic) chemical groups. The
molecule positions itself at the oil/water interface with its hydro-
philic portion in the water phase and its lipophilic portion in the oil
phase. The ratio of hydrophilic to lipophilic sites (HLB) contained in
each surfactant molecule determines the type and stability of the re-
sulting dispersion. A surfactant that is principally hydrophilic dis-
perses oil in water; while one that is principally lipophilic disperses
water in oil.
-------
SECTION 2
CONCLUSIONS
The following conclusions resulted from this test:
• The OHMSETT modification of the five-bar gate proved to be the
most effective device for breaking up a 1-mm thick oil slick
into droplets, as measured by the depth of droplet penetration.
• There was no clear relationship between interfacial tension,
tow speed or waves, and droplet penetration depth that was
applicable to all four test devices.
Penetration depths measured with the five-bar gate were in
good agreement with previous experimental work done in the
United Kingdom (1).
To put these conclusions in proper context, it should be recognized
that several potentially important variables were held constant—slick
thickness, oil specific gravity, and oil viscosity. Testing the effects
of these variables is recommended for future work.
In general, as speed increased, performance increased for each
device, passed through an optimum, and then decreased. The deepest
droplet penetration of the unaltered oil (when no waves were present)
was observed at a speed of 1.5 m/s for the fire hoses and at 2.0 m/s for
the boat and motor and for the five-bar gate. Towing the modified five-
bar gate at 2.0 m/s caused oil droplets to penetrate to the tank bottom
(2.4 m); therefore, optimum speed and maximum penetration depth for
this device could not be obtained in this test tank.
Droplet penetration was generally not affected by wave action.
When regular waves of 0.3-m height and 13.7-m length were present, depth
of droplet penetration of unaltered oil was not affected when using fire
hoses, increased for the standard five-bar gate, and decreased when
using the boat and motor. Lowering the IFT (interfacial tension) to 2 x
10"3 N/m and using the regular waves, greater droplet penetration was
observed for the fire hoses and the boat and motor, with no effect seen
for the five-bar gate. In the presence of a 0.3-m harbor chop, the
depth of oil droplet penetration decreased for the boat and motor, but
was unaffected for the other devices.
Lowering of IFT from 18 x 10~3 N/m to 2 x 10~3 N/m also did not
produce a general trend in device performance. Fire hoses produced less
-------
penetration, but the five-bar gate produced more penetration. More
penetration was also observed with the boat and motor at speeds under
1.5 m/s and less penetration was observed at speeds from 1.5 m/s to 2.5
m/s. Because of time considerations, the modified five-bar gate was not
tested with this test mixture.
-------
SECTION 3
RECOMMENDATIONS
A program should be undertaken to investigate and develop other
means of physical mixing.
Since the oil droplets tend to be more clearly visible against a
dark surface than a light surface, a grid with alternating black and
white squares should be used for better resolution of the oil droplets.
An underwater motorized drive camera (on a mount moving with the
mixing device) should give better results than photographing through the
tank window. If this camera is positioned closer to the surface and
pointed at a larger grid which is either painted on the tank wall or
moving with the test device, a much better resolution of the oil drop-
lets would result.
Future testing of mixing energy application devices should incor-
porate dispersant application systems as well as additional modifications
to the five-bar gate. These may include different configurations of
pipe sections extending below the water surface and oriented at dif-
ferent angles with respect to towing direction.
-------
SECTION 4
MATERIALS AND METHODS
OHMSETT DESCRIPTION
The OHMSETT facility (Appendix A), located in Leonardo, New Jersey,
at the Naval Weapons Station Earle, was built specifically for the
testing of oil and hazardous materials containment and recovery equip-
ment. The tank is 203.3-m long with a water depth of 2.44 m, and waves
can be generated up to 0.68-m high and 28.0-m long. The tank is filled
with seawater from Raritan Bay (salinity 16 ppt).
SELECTION OF EQUIPMENT FOR TESTS
Each major type of dispersant mixing device was represented during
testing.
Equipment used for the fire hose testing consisted of two nozzles
with a. 1.3-cm aperture pointed downward over the aft end of the bridge
(Figure 1). The nozzles were attached to two 15.2-m long, 3.8-cm dia-
meter double jacketed cotton fiber hoses.
An open motorboat 3.66-meters long with a beam of 1.2 meters was
used. The motor was a 55.9-kw (7.5 horsepower) standard outboard motor
(Figure 2).
The five-bar gate, fabricated according to specifications supplied
by the Warren Springs Laboratory (8), is basically a wooden pallet 1.21-
m long and 0.91-m wide. The gate is towed by cables attached to eye
bolts underneath the front corners of the device. (Figures 3 and 4).
A modified version of the five-bar gate was fabricated by attaching
15.2-cm sections of 5-cm diameter pipe, cut in half, to the bottom of
the device. These pipe sections extended straight down and were oriented
so that the interior (concave) facing was toward the forward end of the
device. Thirty-five of these sections were attached in four rows.
(Figures 5 and 6).
Waves were photographed against a grid painted on the test tank's
east wall to measure the height and length. Their period was measured
by stopwatch.
Tow speed data was measured by a DC tachometer which was mounted on
the motor shaft of the bridge drive.
-------
Figure 1. Photograph of fire hose nozzle.
Figure 2. Photograph of motorboat.
;
-------
O3
Leading Edge
Member
(Cross Section Shown Below)
Topside of gate facing up
Bottom of gate facing down
End battens & cross
members made by
cutting 2.74 m by
0.3 m (unplaned)
boards down center
with cross members
nailed to battens,
5 nails per joint
(spacing to be equal to
width of boards
after sawing).
Shakeproof nut
5.72 cm
1.27 cm Hhit. Dynamo
Collar Eyebolt
7.62 cm Shank
Figure 3. Diagram of five-bar gate.
-------
Figure 4. Photograph of the standard five-bar gate.
Figure 5. Photograph of the modified five-bar gate.
-------
m
Topside
of Gate
Pipe half-section
Towing eye-bolt
Figure 6. Modified five-bar gate (shown upside down).
-------
PHOTOGRAPHIC DOCUMENTATION
An important aspect of the test was the photographing of oil drop-
lets against a vertical grid through an observation window, in the side
of the tank. A 16-mm movie camera, operating at 64 frames per second
("slow motion") was aimed at a 1.22-m x 2.44-m board upon which were
painted 30.5-cm squares. One of the squares was further broken down
into 2.54-cm squares. Figure 7 shows the location of the grid, as well
as other facility modifications required for this project.
TEST FLUIDS
Sunvis #31, a paraffin-based lubricating stock, was used straight,
and mixed with either 0.05% or 0.025% Igepal CO-430 surfactant. As can
be seen from Table 1 (in Section 1), all three test fluids had essen-
tially identical surface tension and specific gravity. Viscosity varied
over a narrow range, but interfacial tension varied by a factor of 10.
Tank Wall
Tow Direction
Photography grid
1.22 m x 2.44 m, top
0.2 m below water surface
Oil distribution system
5.08 cm pipe, 7 spray
nozzle
Tank Wall
Test Device
r
i
i
Observation
Window
2.4 m
I
Figure 7. Facility modifications (plan view).
11
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SECTION 5
EXPERIMENTAL PROCEDURES
TEST MATRIX DESIGN
The matrix design was based on variations in interfacial tension,
tow speed, and wave condition. The tests were designed to establish
penetration depth of the oil droplets after the mixing devices had acted
on the slick. Test matrices for each device are listed in Table 2.
Test Procedures are given in Appendix B.
All three devices were tested at a slick thickness of 1 mm and
slick width of 1 meter. Interfacial tension of the three test fluids
was 18 x 10"3 N/m, 8 x 10~3 N/m, or 2 x 10~3 N/m. Tow speed ranged from
1.01 to 2.54 m/s. Waves were adjusted to one of three conditions;
calm, 0.3-m high by 13.7-m long regular, and 0.3-m high harbor chop.
The fire hoses were pre-tested to determine the nozzle angle for
maximum penetration of the water stream. Depth of penetration for a 45°
nozzle angle was observed to be 0.46 m; for 60°, 0.76 m; for 75°, 0.91
m; and for 90°, 1.07 m. Consequently, the water stream from the nozzle
was aimed straight down at the tank surface during the main test series.
The towing force on the five-bar gates was measured by a load cell
which was connected to the towing cable. This information was used to
compute the applied mixing energy (see Appendix C).
12
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TABLE 2. PRIMARY TEST MATRIX
Test no.
1. A1 B2 C3
2. A B C
3. A B C
4. A B C
5. A B C
6. A B C
7. A B C
8. A B C
9. A B C
10. A B C
11. A B C
12. A B C
13. A B C
14. A B C
15. A B C
16. D*
17. D
18. A B C
19. A B C
20. A B C
% Surfactant
0
0
0
0
0
0.025
0.025
0.025
0.025
0.025
0.05
0.05
0.05
0.05
0.05
0
0
0.025
0.05
0
Interfacial
tension
(xlO~3N/m)
18
18
18
18
18
8
8
8
8
8
2
2
2
2
2
18
18
18
8
2
Speed
m/s
1.02
1.52
2.03
2.54
2.54
1.02
1.52-
2.03
2.54
2.54
1.01
1.52
2.03
2.54
2.54
2.54
2.54
2.54
1.02
2.03
Wave
Calm
Calm
Calm
Calm
0.3 m 4 sec.
Calm
Calm
Calm
Calm
0.3 m 4 sec.
Calm
Calm
Calm
Calm
Calm
Calm
Calm
0.3 m HC
0.3 m HC
0.3 m HC
Fire hose.
2Motor boat.
3Five-bar gate.
''Modified five-bar gate.
13
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SECTION 6
RESULTS AND DISCUSSION
In general, droplets did not penetrate the water column very deeply.
The exception was the modified five-bar gate which drove the oil drop-
lets to the bottom of the tank. It was noted that the drops exhibited a
tendency to rise back to the water surface within fifteen minutes after
passage of the test device. Additional effort in improving the existing
mixing devices could make much more mixing energy available.
TABLE 3. MAXIMUM DROPLET PENETRATION (cm) FOR DIFFERENT INTERFACIAL
TENSIONS IN CALM WATER (AT VARYING TOW SPEEDS)
Device
IFT
xlQ-3N/m
Observed
Maximum droplet
penetration cm
Tow speed of
observed max.
penetration m/s
Five-bar gate
Fire hoses
Boat and motor
Modified five-bar
gate
18
8
2
18
8
2
18
8
2
18
35.5
35.5
40.6
121.9
25.4
40.6
125
116
61
244
2
1
1
1.5
2.5
1.5
2
1.5
1.5
4.1
Results obtained from the unaltered oil in calm water (summarized
in Table 3) indicate that fire hoses were best at speeds of 1.8 m/s and
below because they produced more force per square meter. Maximum pene-
tration depth was 1.2 m at 1.52 m/s in calm water.
A maximum penetration depth of 125 cm was observed at 2.03 m/s for
the boat and motor. Below this speed, less power was available to the
propeller to disperse the oil, while above this speed the hull of the
boat separated the slick so that very little oil was affected by the
propeller wash and wake of the boat.
14
-------
The five-bar gate's maximum oil droplet penetration of 36 cm was at
2.03 m/s. Oil tended to go under the first bars and then go over the
back bars, riding on a cushion of water. Oil dispersed by the gate was
in finer droplets than it was when the fire hoses or the boat and motor
were used, but the depth of penetration was less.
The modified five-bar gate drove the oil droplets to the tank
bottom (244 cm) at a speed of 2 m/s. Table 4 summarizes results in
waves.
TABLE 4. MAXIMUM DROPLET PENETRATION FOR DIFFERENT WAVE
CONDITIONS AND AN IFT OF 18xlQ-3N/m at 2.5 m/s
Device
Five-bar gate
Fire hoses
Boat and motor
Wave
Condition
Calm
0.3 m HC
0.3mxl3.7m
Calm
0.3 m HC
0.3mxl3.7m
Calm
0.3 m HC
0.3mxl3.7m
Penetration
Depth cm
20.3
20.3
38.1
25.4
25.4
25.4
35.5
30.0
20.3
Tow speed
m/s
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
The 0.3-m harbor chop wave did not affect the penetration depth of
the fire hoses. However, it caused the drops which did penetrate the
water to remain suspended longer. This phenomenon was exhibited for all
devices tested in the harbor chop wave. The performance of the boat and
motor was decreased for two reasons: the wave action caused the slick
to be uneven across the boat's path; and the waves caused the boat hull
to pound, splashing the oil to the sides, out of the path of the pro-
peller. The five-bar gate rode this wave well, and droplet penetration
was unaffected.
In the 0.3-m high, regular wave, penetration depth for the fire
hoses was observed to increase slightly. Again, wave-hull interactions
caused the oil to be driven away from the motorboat propeller. When
pure oil was used, penetration depth slightly increased in the regular
wave for the five-bar gate. However, when the IFT was lowered, pene-
tration depth reduced to that of the calm condition. In addition,
lowered IFT resulted in smaller oil drop diameter, and therefore, lower
rise velocities. Accordingly, oil droplets remained in the water column
longer. The effect of various types of waves on the mixing energy
required to effectively disperse oil slicks is becoming more important
with the development of dispersant chemicals that either need no mixing
or are mixed by the wave energy alone (4,5).
15
-------
Lowering the oil/water interfacial tension caused the fire hoses to
lose effectiveness. The slick was observed to spread away from the
current. This was caused by the fire hoses impacting the tank water
surface relatively more rapidly with lowered IFT. This meant less oil
was present to be affected by the downward force of the hose streams
(and hence less penetration occurred).
By contrast, the boat and motor gained in effectiveness as IFT was
lowered. This may have been caused by the decrease in the amount of
energy needed to overcome the lower IFT and to form an oil drop sub-
surface near the hull of the boat. These drops would follow the hull
back to the propeller, and the propeller would then drive the drops down
into the water column. Because the boat's propeller was the major
factor in depth of penetration for the boat and motor, any test con-
dition which would cause the oil to be more affected by the propeller
would increase the penetration depth.
Five-bar gate performance was unaffected by lowering the IFT.
Previous work at OHMSETT, with three test fluids representing a
range of specific gravity from 0.710 to 0.975, indicated a definite
correlation between larger droplet size and greater penetration depth
with the higher specific gravity test fluids (9). Therefore, increasing
the specific gravity of the spilled floating oil would make mixing and
dispersing easier.
A compilation of all data derived from these tests is available
in Appendix C.
16
-------
REFERENCES
1. Inter-governmental Maritime Consultative Organisation, Sub-committee
on Marine Pollution. 1972 Manual on Oil Pollution: Practical
Information on Means of Dealing with Oil Spillages. (1ZE. I.M.C.O.,
1972). pp. 32-39.
2. Canevari, G.P. General Dispersant Theory. In: Proceedings of Joint
Conference on Prevention and Control of Oil Spills, American Petroleum
Institute, Washington, D.C., 1969. pp. 171-177.
3. Canevari, G.P. Oil Spill Dispersants - Current Status and Future
Outlook. In: Proceedings of Joint Conference on Prevention and
Control of Oil Spills, American Petroleum Institute, Washington,
B.C., 1970. pp 263-270.
4. Canevari, G.P. Development of the Next Generation Chemical Dispersants.
In: Proceedings of Joint Conference on Prevention and Control of
Oil Spills, American Petroleum Institute, Washington, D.C., 1969.
pp. 231-240.
5. Canevari, G.P. A Review of the Utility of Self-Mixing Dispersants
in Recent Years. In: Proceedings of Joint Conference on Prevention
and Control of Oil Spills, American Petroleum Institute, Washington,
D.C., 1975. pp. 337-342.
6. Poliakoff, M.Z. Oil Dispersing Chemicals. FWPCA-15080FHS 05/69,
U.S. Environmental Protection Agency, Cincinnati, Ohio, 1969. 27
pp.
7. Battelle Memorial Institute - Pacific Northwest Laboratories. Oil
Spill Treating Agents Test Procedures - Status and Recommendations.
American Petroleum Institute, Washington, D.C., 1970. pp. 14-36.
8. Smith, J. and Shuttleworth, F. Development of the Warren Springs
Laboratory Dispersant Spraying Equipment. United Kingdom Department
of Trade and Industry. London, England, 1971. 54 pp.
9. Freestone, F.J., W.E. McCracken, and J.P. Lafornara. Performance
testing of spill control devices on floatable hazardous materials.
In: Proceedings of National Conference on Control of Hazardous
Material Spills, Information Transfer, Inc., Rockville, Maryland,
1976. pp. 326-331.
17
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APPENDIX A
OHMSETT TEST FACILITY
Figure A-l. OHMSETT Test Facility,
GENERAL
The U.S. Environmental Protection Agency is operating an Oil and
Hazardous Materials Simulated Environmental Test Tank (OHMSETT) located
in Leonardo, New Jersey (Figure A-l). This facility provides an environ-
mentally safe place to conduct testing and development of devices and
techniques for the control of oil and hazardous material spills.
The primary feature of the facility is a pile-supported, concrete
tank with a water surface 203 metres long by 20 metres wide and with a
water depth of 2.4 metres. The tank can be filled with fresh or salt
water. The tank is spanned by a bridge capable of exerting a force up
to 151 kilonewtons, towing floating equipment at speeds to 3 metres/second
18
-------
for at least 45 seconds. Slower speeds yield longer test runs. The
towing bridge is equipped to lay oil or hazardous materials on the
surface of the water several metres ahead of the device being tested, so
that reproducible thicknesses and widths of the test fluids can be
achieved with minimum interference by wind.
The principal systems of the tank include a wave generator and
beach, and a filter system. The wave generator and absorber beach have
capabilities of producing regular waves to 0.7 metre high and to 28.0
metres long, as well as a series to 1.2 metres high reflecting, complex
waves meant to simulate the water surface of a harbor or the sea. The
tank water is clarified by recirculation through a 0.13 cubic metre/second
diatomaceous earth filter system to permit full use of a sophisticated
underwater photography and video imagery system, and to remove the
hydrocarbons that enter the tank water as a result of testing. The
towing bridge has a built-in skimming barrier which can move oil onto
the North end of the tank for cleanup and recycling.
When the tank must be emptied for maintenance purposes, the entire
water volume, of 9842 cubic metres is filtered and treated until it
meets all applicable State and Federal water quality standards before
being discharged. Additional specialized treatment may be used whenever
hazardous materials are used for tests. One such device is a trailer-
mounted carbon treatment unit for removing organic materials from the
water.
Testing at the facility is served from a 650 square metres building
adjacent to the tank. This building houses offices, a quality control
laboratory (which is very important since test fluids and tank water are
both recycled), a small machine shop, and an equipment preparation area.
This government-owned, contractor-operated facility is available
for testing purposes on a cost-reimbursable basis. The operating con-
tractor, Mason & Hanger-Silas Mason Co., Inc., provides a permanent
staff of fourteen multi-disciplinary personnel. The U.S. Environmental
Protection Agency provides expertise in the area of spill control tech-
nology, and overall project direction.
For additional information, contact: John S. Farlow, OHMSETT
Project Officer, U.S. Environmental Protection Agency, Research and
Development, lERL-Ci, Edison, New Jersey 08817, 201-321-6631.
19
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APPENDIX B
TEST PROCEDURES
A step-by-step procedure for the testing program is given below in
the following format: Manpower Allocations (Figure B-l), Pre-test
Checklist, and Test Sequence.
MANPOWER ALLOCATIONS
1. Test Director - responsible for running the tests according to the
prescribed test matrix and test procedure. Manages the test personnel.
2. Photographer - documents the test with 35-mm color slides and 16-mm
color motion pictures.
3. Oil distribution operator - maintains the test fluid thickness at
1 mm at the beginning of each test run. Assists with other duties
as needed.
4. Bridge and wave generator operator - operates the wave generator
and bridge, and collects data for ambient conditions.
PRE-TEST CHECKLIST
To ensure that all test systems and equipment were maintained and
ready for the test day, the following checklist was used prior to the
first test run:
1. Bridge drive system working.
2. Wave generator system operational.
3. Test device operational.
4. Test instrumentation operational.
5. Test fluid ready.
6. Test fluid distribution system operational.
7. Test support equipment operational.
8. Photographic systems ready.
9. Test personnel prepared and ready.
10. Complete all pre-run data sheets and checklists.
TEST SEQUENCE
Test Procedure - Fire Hoses Penetration Angle Pre-Test
1. Position bridge along tank to facilitate measuring the
20
-------
depth of penetration of the water streams into the water
against the grid.
2. Place fire hose nozzles to give proper angle of water stream
to water's surface.
3. Start pump.
4. Open fire hose nozzles.
5. Observe and document penetration of fire hose streams against
grid from window in tank wall.
6. Repeat steps 2-5 at next angle of incidence. (Angles used
were 45°, 60°, 75°, and 90°).
Fire Hoses Tank Testing
1. Determine correct bridge speed, oil type, and oil flow rate
from test plan.
2. Ensure
2. Ensure photographers are ready and initiate waves, if called
for.
3. Start fire hose streams.
4. Start bridge moving at correct speed.
5. Start oil distribution.
6. Start photographic documentation to determine maximum penetration
of oil droplets caused by fire hose streams.
7. Stop photographic documentation after maximum penetration has
been reached.
8. Stop oil distribution.
9. Stop hose streams.
10. Stop bridge and stop waves, if any.
11. Lower skimmer bar, and skim oil in preparation for the next
test.
12. Repeat steps 1-11 for each tow speed and wave condition.
Test Procedure - Motor Boat
1. Determine correct bridge speed.
2. Ensure photograpers are ready and initiate waves, if called for.
21
-------
3. Start bridge moving at correct speed.
4. Match boat speed with bridge speed.
5. Start oil distribution.
6. Start photographic documentation to determine maximum penetration
of oil droplets caused by boat wake and propeller wash.
7. Drive boat between grid and camera.
8. Stop photographic documentation after the oil drops reach
maximum penetration depth.
9. Stop oil distribution system.
10. Return motor boat to starting position for next test.
11. Stop bridge and waves, if any.
12. Lower skimmer bar and skim oil in preparation for the next
test.
13. Figure B-l shows manpower allocations for the motor boat
testing.
Test Procedure - Five-Bar Gate and Modified Five-Bar Gate
1. Determine correct bridge speed, oil type, and oil flow rate
from test plan.
2. Ensure photographers are ready and initiate waves, if necessary.
3. Start bridge moving at correct speed.
4. Check gate for proper towing alignment.
5. Start oil distribution.
6. Start photographic documentation to determine maximum penetration
of oil droplets caused by gate turbulence.
7. Stop photographic documentation after oil drops reach maximum
penetration depth.
8. Stop oil distribution system.
9. Stop bridge and stop waves, if any.
10. Lower skimmer bar and skim test oil in preparation for the
next test run.
22
-------
Tank
Control
Room
©
Tow Direction
Boat
1 Bridge & Wave Generator Operator
2 Oil Distribution Operator 4
3 Test Director 5
Photographer
Boat Operator
Figure B-l. Manpower distribution.
-------
APPENDIX C
TEST RESULTS
DISPERSANT MIXING DEVICES
The following appendix includes raw data compiled from individual
test runs. The tables include:
Test identification
Device speed
Mixing energy*
Oil/water interfacial tension
Wave characteristics
Maximum oil drop penetration distance
*Fire hoses: K.E. = 1/2 mv2
= 1/2 (flow rate) (water density/g) (discharge velocity)
K.E. K.E. number of nozzles
area minute/nozzle sweep width x tow speed
Five-bar gate: K.E. = 1/2 mv2
= 1/2 (tow force/g) (tow velocity)2
K.E. — K.E.
area surface area of gate
24
-------
TABLE C-l. FIRE HOSE DATA
NJ
Ul
Test
no.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
18
19
20
Tow speed
m/s
1.02
1.52
2.03
2.54
2.54
1.02
1.52
2.03
2.54
2.54
1.02
1.52
2.03
2.54
2.54
2.54
2.54
2.54
Mixing
energy
J/m2
418.7
278.8
209.9
167.9
167.9
418.7
278.8
209.9
167.9
167.9
418.7
278.8
209.9
167.9
167.9
167.9
167.9
167.9
Oil IFT
xlO~3N/m
18
18
18
18
18
8
8
8
8
8
2
2
2
2
2
18
8
2
Wave
height length period
m m s
Calm
ii
Calm
Calm
0.3 13.7 4
Calm
Calm
Calm
Calm
0.3 13.7 4
Calm
Calm
Calm
Calm
0.3 13.7 4
0.3HC*
0.3HC
0.3HC
Droplet
Penetration
cm
76.2
121.9
61.0
25.4
25.4
20.3
20.3
20.3
25.4
30.5
35.6
40.6
30.5
20.3
30.5
20.4
25.4
20.3
*HC - Harbor Chop
-------
TABLE C-2. BOAT AND MOTOR DATA
ISJ
Test
no.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
18
19
20
Velocity
m/s
1.02
1.52
2.03
2.54
2.54
1.02
1.52
2.03
2.54
2.54
1.02
1.52
2.03
2.54
2.54
2.54
2.54
2.54
Oil IFT
xlO~3N/m
18
18
18
18
18
8
8
8
8
8
2
2
2
2
2
18
8
2
Wave
height length
m m
Calm
Calm
Calm
Calm
0.3 13.7
Calm
Calm
Calm
Calm
0.3 13.7
Calm
Calm
Calm
Calm
0.3 13.7
0.3HC*
0.3HC
0.3HC
Droplet
period Penetration
s cm
38.1
27.9
125.0
35.6
4 30.0
81.3
116.8
61.0
66.0
4 33.0
61.0
61.0
50.8
20.3
4 50.8
20.3
35.6
50.8
*HC - Harbor Chop
-------
TABLE C-3. FIVE-BAR GATE DATA
N3
Test
no.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
18
19
20
Tow speed
m/s
1.02
1.52
2.03
2.54
2.54
1.02
1.52
2.03
2.54
2.54
1.02
1.52
2.03
2.54
2.54
2.54
2.54
2.54
Mixing
energy
J/m2
7.6
30.1
95.1
211.0
211.0
7.6
30.1
95.1
211.0
211.0
7.6
30.1
95.1
211.0
211.0
211.0
211.0
211.0
Wave Droplet
Oil IFT
xlO~3N/m
18
18
18
18
18
8
8
8
8
8
2
2
2
2
2
18
8
2
height length period Penetration
m m :g
Calm
Calm
Calm
Calm
0.3 13.7 4
Calm
Calm
Calm
Calm
0.3 13.7 4
Calm
Calm
Calm
Calm
0.3 13.7 4
0.3HC*
0.3HC
0.3HC
cm
20.3
25.4
35.6
20.3
38.1
35.6
20.3
20.3
20.3
20.3
40.6
30.5
30.5
30.5
20.3
30.5
20.3
*HC -
Harbor Chop
TABLE C-4.
MODIFIED FIVE-BAR GATE DATA
Test
no.
16
17
Velocity
m/s
1.02
2.03
Oil
xlO
Wave
IFT height length period
~3N/m m m s
18 Calm
18 Calm
Droplet
Penetration
cm
> 91.4
>244.0
-------
NJ
00
1.3 _
1.2
1.1
1.0
0.9
0.8
55 0.7
o
H
W
g 0.5
0.4
0.3
0.2
0.1
0.0
Five bar gate
Fire hoses
Boat and motor
OIL IFT
O 18 x 10"3 N/m
D 18 x 10~3 N/m
X D
-a
I
I
I i
I
I
1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6
TOW SPEED (m/s)
Figure C-l. Drop penetration vs. tow speed, no wave.
j i
-------
N5
VO
1.3
1.2
1.1
1.0
0.9
0.8
1 0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Q Five-bar gate
Q Fire hose
A Boat and Motor
J.
1
_L
J L
_L
J
Figure C-2.
4 5 6 78 9 10 11 12 13 14 15 16 17 18
OIL IFT (y. 10"3 N/m)
Drop penetration vs. oil IFT at tow speed of 1.02 m/s, no wave.
-------
u>
o
a
s
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
O Five-bar gate
n Fire hose
A Boat and motor
I
I
L
I
I
Figure C-3.
45 6 7 8 9 10 11 12 13 14 15 16 17 18
OIL IFT (x 10"3N/m)
Drop penetration vs. oil IFT at tow speed of 1.52 m/s, no wave.
-------
w
1.3 r-
1.2
1.1 h
l.D
0.9
0.8
§ 0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Five-bar gate
D Fire hose
A Boat and motor
8
10
11
12 13 14 15 16 17 18
Figure C-4.
OIL IFT (x 10~3 N/m)
Drop penetration vs. oil IFT at tow speed of 2.03 m/s, no wave.
-------
CO
to
1.3
1.2
1.1
1..0
0.9
0.7
0.
w
55
0.5
0.4
0.3
0.2
0.1
0.0
O Five-bar gate
D Fire hose
^ Boat and motor
I i
I
1
I
_L
1 23 4 5 67 8 9 10 11 12 13 14 15 16 17 18
OIL IFT (x 10"3 N/m)
Figure C-5. Drop penetration vs. oil IFT at tow speed of 2.54 m/s, no wave.
-------
1.3 r-
1.2
1.1
1..0
0.9
0.8
§
I °'7
w 0.6
0.5
0.4
0.3
0.2
0.1
0.0
0 Five-bar gate
E Fire hose
A Boat and motor
I I II
I
J I
I
J I
i I
I
I j
Figure C-6.
3 45 6 7 8 9 10 11 12 13 14 15 16 17 18
OIL IFT (x 10~3 N/m)
Drop penetration vs. oil IFT at tow speed of 2.54 m/s, with 0.3 tn harbor chop,
-------
1.4
1.3
1,2
1.0
0.9
w 0.7
0.6
0.5
0.4
0.3
0.2
0.1
O Five-bar gate
Q Fire hose
A Boat and motor
I
I
I
12 13 14 15 16 17
18
123456789 10 11
OIL IFT x 10~3 N/m
Figure C-7. Drop pentration vs. oil IFT with tow speed of 2.54 m/s, with 0.3 m regular wave.
-------
OJ
01
§
la
w
1.3 p
1.2 „
1.1 U
1..0
0.9
0.8
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Five-bar gate
a
Fire hose
A Boat and motor
I
I
I
I
I
I
1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6
Figure C-8. Drop penetration vs. tow speed (ra/s) at IFT = 18 x 10~3 N/m, no wave.
-------
u>
6
6
M
H
W
1.3 ~
1.2 -
1.1
1.0
0.9
0.8
0.5
0.4
0.3
0.2
0.1
0.9
O Five-bar gate
Q Fire hose
A Boat and motor
- D
I
I
I
I
J_
I
1
I
1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 275 2TF
Figure C-9. Drop penetration vs; tow speed (m/s) at IFT = 8 x 10~3 N/m, no vjave.
-------
to
l.3r-
1.2
1.1
1.0
0.9
0.8
§ 0.7
M
H
W
z
W
0.5
0.4
0.3
0.2
0.1
0.0
O Five-bar gate
£j Fire hose
A Boat and motor
1
JL
1
J.
1
J.
J L
I
_L
1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6
Figure C-10. Drop penetration vs. tow speed (m/k) at IFT = 2 x 10~3 N/m, no wave.
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-78-128
3. RECIPIENT'S 'XCCESSION'NO.
4. TITLE AND SUBTITLE
TECHNIQUES FOR MIXING DISPERSANTS WITH SPILLED OIL
5. REPORT DATE
June 1978 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Gary F. Smith
a. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Mason & Hanger-Silas
P. 0. Box 117
Leonardo, New Jersey
Mason Co., Inc.
07737
10. PROGRAM ELEMENT NO.
1NE623
|11. CONTRACT/GRANT NO.
68-03-0490
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Lab.
Office.of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
- Cinn, OH
13. TYPE OF REPORT AND PERIOD COVERED
Final April 22 - May 6. 1976
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The effective use of some oil spill dispersants requires the addition of mixing
energy to the dispersant-treated slick. Various methods of energy application
have included the use of fire hose streams directed to the water surface, out-
board motors mounted on work boats, and the five-bar gate, a pallet-like device
towed on the surface behind vessels of opportunity. ;
The U.S. Environmental Protection Agency sponsored this test program at their Oil
& Hazardous Materials Simulated Environmental Test Tank (OHMSETT) to evaluate the
above devices as well as a modified version of the five-bar gate. Three test fluid
mixtures with different interfacial tensions were distributed onto the water sur-
face, and each mixing device was towed through them at speeds from 1.02 m/s to
2.54 m/s in three wave conditions. Droplet penetration was documented via under-
water photography.
Analysis of the results'showed that the modified five-bar gate produced the
greatest overall penetration (2.4 m) at a tow speed of 2/0 m/s. In general, per-
formance was unaffected by wave action, and variations in interfacial tension
produced no observable trend among all devices.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Water pollution
Performance tests
Oils
Dispersers (agitators)
Dispersants
Oil spill cleanup
Protected waters
Offshore waters
68D
13. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport/
UNCLASSIFIED
21. NO. OF PAGES
48
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
•if U.S GOVERNMENT PRINTING OFFICE: 1978-757-140/1329
38
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