EPA-600/2-78-093
May 1978
Environmental Protection Technology Series
OHMSETT "HIGH SEAS" PERFORMANCE TESTING:
MARCO CLASS V OIL SKIMMER
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
-------
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.
-------
EPA-600/2-78-093
May 1978
OHMSETT "HIGH SEAS" PERFORMANCE TESTING:
MARCO CLASS V OIL SKIMMER
by
G.F. Smith and W.E. McCracken
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 efficient
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 under a variety of condi-
tions of a commercial, sorbent belt, oil skimmer used by the U.S. Navy.
Based on this preliminary series of tests, judgments on controllable
settings for optimizing operational efficiency can be made. 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 in Edison, New Jersey.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
iii
-------
ABSTRACT
A MARCO Class V oil skimmer was tested at the U.S. Environmental
Protection Agency's OHMSETT facility to determine the device's "high
seas" performance characteristics. Performance data was obtained for
several simulated offshore wave conditions at various collection speeds.
Skimmer efficiency was determined at various belt speeds and induction
pump rates in order to define optimum skimmer settings and to better
define oil/water separator needs. This report of testing done under
Contract No. 68-03-0490, Job Order No. 22, by Mason & Hanger-Silas Mason
Co., Inc., for the U. S. Environmental Protection Agency covers the
period September 27, 1976 to October 1, 1976 with work completed
January 14, 1977.
iv
-------
CONTENTS
Foreword ill
Abstract iv
Figures vi
Tables vi
Abbreviations and Symbols vii
Acknowledgment viii
1. Introduction 1
2. Conclusions 2
3. Recommendations 3
4. Test Device 4
5. Experimental Procedures 13
6. Results and Discussion 19
Bibliography 24
Appendices
A. OHMSETT Description 25
B. Filterbelt Principles 27
C. Data and Graphics 29
-------
FIGURES
Number Page
1 MARCO Class V Skimmer during OHMSETT wave testing 5
2 MARCO Class V Skimmer 6
3 MARCO Class V Skimmer under tow (transport only) 8
4 MARCO Class V Skimmer towed for oil recovery 9
5 MARCO filterbelt during oil recovery 10
6 Squeeze roller assembly removing oil from the filterbelt . 10
7 Induction pump mounted in skimmer bottom behind and
below the filterbelt (conveyor shown here in the
"up", or travel position) 11
8 Cross-section of the filterbelt 12
9 Graph of kinematic viscosity as a function of temperature
for Sunvis 1650 oil 16
10 Test tank layout of MARCO V 17
11 Oil recovery for the MARCO Class V 20
12 Oil droplets washed from the filterbelt being ejected
from the skimmer by the induction pump 21
13 Water retention characteristics (recovery efficiency)
of filterbelt 22
TABLES
Number
1
2
3
Condensed specifications MARCO Class V ocean skimmer
Proposed test matrix
Summary of results
7
14
23
vi
-------
ABBREVIATIONS
ABBREVIATIONS AND SYMBOLS
BWD
bbls
cm
m3/s
DWP
°C
gals
GPM
HC
HP
IT
m
m3
m/s
m2/s
mm
min
N/m2
OHMSETT
OPER
OPT
%
Ibs
Ibs/in
RPM
Sp.
ST
VDU
w/
w/o
h
1
Gr.
—backward
—barrels
—centimeters
—cubic meters per second
—deep water ports
—degrees Celsuis
—gallons
—gallons per minute
—harbor chop
—horsepower
—interfacial tension
—meter
—cubic meters
—meters per second
—meters squared per second (viscosity measurement)
—millimeters
—minute
—newtons per square meter
—Oil and Hazardous Materials Simulated Environmental
Test Tank
—operator
—optimum
—percent
—pounds
—pounds per inch
—revolutions per minute
—specific gravity
—surface tension
—vacuum distillation unit
—with
—without
—wave height
—wave length
vii
-------
ACKNOWLEDGMENT
J.E. Sholander, Naval Surface Weapons Center, Dahlgren Laboratory,
Dahlgren, VA and J.H. Friel, Naval Sea Systems Command, Supervisor of
Salvage, Washington, D.C. provided valuable help during planning and
testing phases. The skimmer was loaned for testing through the courtesy
of the Naval Sea Systems Command, Supervisor of Salvage, Washington, DC.
P.L. Forde, MARCO Pollution Control, Seattle, WA provided expertise
in operation of the skimmer and information on the skimmer's operating
principles.
viii
-------
SECTION 1
INTRODUCTION
Increased U.S. dependence on oil shipped by water, together with
increased size of oil-carrying tankers and offshore docking facilities
(deep water ports), create a greater probability of a major spill, and
indicate a need for oil containment and clean up devices capable of
operating in wave and current conditions found in the offshore environ-
ment. Recent oil spills, such as the Argo Merchant, emphasize the
problem of trying to clean up massive oil spills in the offshore
environment.
A MARCO Pollution Control Class V Oil Skimmer was tested at the
U.S. Environmental Protection Agency's Oil and Hazardous Materials
Simulated Environmental Test Tank (OHMSETT) in Leonardo, N.J. Objectives
of the test program were to:
1. Determine performance characteristics of the skimmer operating
in "high seas conditions" generated in the OHMSETT test tank.
2. Determine oil/water separation needs for the skimmer output.
3. Determine optimum skimmer mechanical operating settings.
-------
SECTION 2
CONCLUSIONS
HIGH SEAS PERFORMANCE
The oil recovery rate of the MARCO Class V skimmer rose 60%, from
3.7 x 10~3m3/s to 5.9 x 10~3m3/s as tow speed increased from 0.51 to
1.54 m/s in calm water. Only a 17% increase, from 3 x 10~3m3/s to 3.5
x 10~ m/s, was found in a 0.6 m HC wave over this same tow speed range.
Changing the tow speed from 0.51 to 1.54 m/s did not affect recovery
efficiency in either calm water or in the 1.2 m HC wave. But the
recovery efficiency declined 32%, from 73.6% to 36.8%, in the 0.6 m HC
wave over this same speed range.
Throughput efficiency declined 30%, from 98.5% to 67.9%, as speed
increased from 0.51 m/s to 1.54 m/s in calm water. The throughput
efficiency dropped 64% in the 0.6 m HC wave and 33% in the 1.2 m HC wave
over this same speed range. Thus, increased tow speed caused oil loss
to increase in all cases.
Recovered fluid water content ranged from a minimum of 21.9% to a
maximum maximum of 65.8%. In terms of a water volume rate, this covered
a range from 1.5 x 10~3m3/s to 1.8 x 10~3m3/s (because tests recovering
large fluid volumes contained less water than tests recovering smaller
fluid volumes). The addition of settling tanks between the skimmer and
the separator would lower these figures considerably, since about 20% of
the water in the recovered fluid separated out in 15-30 minutes.
Optimum skimmer operating settings were different for each wave
height condition tested. In calm water, a filterbelt speed of 0.94 m/s
with the induction pump pressure setting of 5.2 x 106 N/m2 and a tow
speed of 1.03 m/s produced the best results. A filterbelt speed of
0.64 m/s and a pressure setting of 3.4 x 106 N/m2 with a tow speed of
0.51 m/s worked best in the 0.6 m HC wave.
It should be noted that because of limited time, this test series
was severely abbreviated, with little opportunity for repeating tests.
-------
SECTION 3
RECOMMENDATIONS
This test program was too abbreviated. A more complete program
should evaluate the effects of varying speed, wave conditions, oil type
and thickness, and device operating parameters such as belt speed and
induction pump speed.
Problems were encountered in measuring the large volumes of fluid
recovered by the skimmer. Because several small tanks were used, to
hold the collected fluid, an inconveniently large number of samples from
each test resulted, each requiring a separate laboratory analysis. Use
of a single larger tank would reduce both the sample load and analysis
time. A more efficient system for collecting the recovery fluid, decanting
the settled water, and sampling the remaining emulsion should be designed
prior to additional testing.
An oil/water separation system to process the fluid recovered would
make the unit more useful. Preferably, the system would be placed in
the recovery line before the onboard storage tanks so that only oil
would need to be stored aboard (while the separated water would be
pumped back to the sea) .
-------
SECTION 4
TEST DEVICE
The MARCO Class V Oil Skimmer is a self-propelled, self-contained
boat 11-m long with a beam of 3.7 m (Figures 1 and 2). Maximum speed of
the vessel is 2.6 m/s. A motor-driven hydraulic drive and a 360°
rotatable propeller provide maneuverability. Table 1 gives a condensed
list of specifications.
The MARCO Class V skimmer may either propel itself to the spill
site and pick up the spill under its own power, or be towed to the site
at higher speeds (Figure 3). Wider swaths at the spill site may be
swept by the addition of collection booms to the skimmer (Figure 4) .
Oil collection is performed by an inclined conveyor with a con-
tinuous filterbelt which retains the oil and lets the water pass through
(Figure 5). Figure 6 shows the belt passing between rollers which
squeezes the oil from the belt into a collection tank. Belt porosity
(to water) permits waves to pass through the belt. An induction pump
(Figure 7) is used behind the belt to aid in water flow through the
filterbelt and to minimize the formation of a head wave forward of the
belt. Figure 8 shows a cross-section of the collection system. Appendix
B provides an explanation of the filterbelt's operating principle.
-------
Figure 1. MARCO Class V skimmer during OHMSETT wave testing.
-------
in the travel mode
Forward
Starboard
Squeezing apparatus
Sorbent
belt
Forward in the oil
collection mode
Figure 2. MARCO Class V Skimmer.
-------
TABLE 1. CONDENSED PACIFICATIONS MARCO CLASS V OCEAN SKIMMER
Particulars
Length, Overall
Beam, Overall
Displacement, R.F.S.
Nav. Draft. R.F.S.
F.O. Capacity
F.W. Capacity
Oil Slops Cap. (42 US gal/bbl)
Shrinkage (Saltwater)
Freeboard R.F.S. Amidships
Freeboard 1/2 P.O., Full Slops
Free Sweep Width
Maximum Belt Submergence
Filterbelt Flow, m3/hr at 0.51 m/s
Induction Pump
Maximum Rated Flow
English
36'-0"
12'-0"
16,480 Ibs.
3'-6"
75 gals.
None
40 bbls.
1360 Ibs. /in.
18"
8"
6'-0"
3'-3"
7850
(1) at 20 HP
8000 GPM
Metric
10.97 m
3.66 m
750 kg
1.07 m
0.38 m3
None
6.4 m3
240 kg/cm
0.46 m
0.20 m
1.83 m
1.0 m
1740 m3/hr
(1) at 14914 W
1817 m3/hr
Propulsion
Main Engine
Speed, R.F.S.
Propulsion Unit
(1) at 100 HP, at 2900 RPM
2.6 m/s
MARCO Hydraulic Drive 360°
Rotation
Equipment
Offload Pump
(1) Progressive Cavity 45.4 m3/hr
Mode of Operation
Navigate
Being towed, high speed or rough sea
Oil Skimming
Forward or Backward (BWD)
Forward
BWD, w/ or w/o Diversion Booms
-------
TOW LINE
00
TOWING
VESSEL
OIL RECOVERY"
VESSEL
Figure 3. MARCO Class V skimmer under tow (transport only).
-------
te^'; .'•;•' '
FLOATING
BOOM
OIL RECOVERY
VESSEL
•^'••''''•''.''V'Y;/',-, *')•;»
/ t * v
Figure 4. MARCO Class V skimmer towed for oil recovery.
-------
Figure 5. MARCO filterbelt during oil recovery.
Figure 6. Squeeze roller assembly removing oil from the filterbelt.
10
-------
Figure 7. Induction pump mounted in skimmer bottom behind and below
the filterbelt (conveyor shown here in the "up", or
travel position).
11
-------
Drive Roller
Support Grating
N>
Belt Scraper
Figure 8. Cross-section diagram of the filterbelt
-------
SECTION 5
EXPERIMENTAL PROCEDURES
The test plan (Table 2) was designed to evaluate performance of the
MARCO Class V Oil Skimmer under conditions as close as possible to those
expected at an offshore oil spill. The skimmer was towed (to simulate
currents) at speeds of 0.51, 1.03, and 1.52 m/s through calm water and
through 0.6 m and 1.2 m harbor chop waves. The test fluid used was a
straight grade lubricating oil with the observed properties given in
Figure 9. Oil film thickness was held constant at three millimeters for
all test runs. Manpower distribution is shown in Figure 10.
Determination of optimum skimmer mechanical settings (belt speed
and induction pump rate) was also incorporated into the test matrix.
Utilizing a best guess for a starting point, then testing at and around
that point in an iterative scheme, the optimum settings were found.
Unusual elements of the procedure for testing this device were:
1. Pre-wetting the belt.
2. Determining steady state.
3. Determining emulsion characteristics.
The conditions of the first run with oil each day were duplicated
in a second run, and the results were compared. The first was considered
a dry-belt test run, while later runs were considered wet-belt runs. No
consistent differences were observed between dry-belt and wet-belt
tests.
Steady state was considered to be reached during a test when the
composition of the recovered oil/water mixture did not vary substan-
tially with time. The skimmer output was sampled every five seconds
after the oil encountered the sorbent belt.
Discrete quantities of the recovered fluid were collected through
a sample port on the exit side of the recovery pump. Analysis of the
oil/water composition gave recovery efficiency. The remainder (majority)
of the recovered fluid was held in 0.82 m3 translucent, polyethylene
containers and allowed to settle. The containers then had three distinct
layers: oil (with a small percentage of water) on top, emulsion (high
percentage of water) and water (with a small percentage of oil) on the
13
-------
TABLE 2. PROPOSED TEST MATRIX.
Test
no.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
Oil
type
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Sun 1650
Belt
speed
m/s
Opt. A
Opt. A+ .15
Opt. A- .15
Opt. A*
Opt. A*
Opt. A*
Opt. A*
Opt. B
Opt. B+ .15
Opt. B- .15
Opt. B*
Opt. B*
Opt. B*
Opt. B*
Opt. C
Opt. C+ .15
Opt. C- .15
Opt. C*
Opt. C*
Opt. C*
Opt. C*
Opt. C*
Opt. B*
Opt. A*
Opt. A*
Opt. B*
Opt. C*
Opt. A*
Opt. B*
Opt. C*
Opt. D
Opt. D+ .15
Opt. D- .15
Opt. D*
Opt. D*
Opt. D*
Opt. D*
Opt. E
Opt. E .15
Opt. E- .15
Opt. E*
Opt. E*
Opt. E*
Induction
pump rate
m3/sxlO~3
None
None
None
Opt. A
Opt. A+
Opt. A+
Opt. A*
None
None
None
Opt. B
Opt. B+
Opt. B-
Opt. B*
None
None
None
Opt. C
Opt. C+
Opt. C-
Opt. C*
Opt. C*
Opt. B*
Opt. A*
Opt. A*
Opt. B*
Opt. C*
Opt. A*
Opt. B*
Opt. C*
None
None
None
Opt. D
Opt. W-
Opt. D-
Opt. D*
None
None
None
Opt. E*
Opt. E+
Opt. E-
Tow
speed
m/s
0.51
0.51
0.51
0.51
0.51
0.51
0.51
1.03
1.03
1.03
1.03
1.03
1.03
1.03
1.52
1.52
1.52
1.52
1.52
1.52
1.52
1.52
1.03
0.51
0.51
1.03
1.52
0.51
1.03
1.52
2.03
2.03
2.03
2.03
2.03
2.03
2.03
2.54
2.54
2.54
2.54
2.54
2.54
Wave
hxl
m
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.6x9.1
0.6x9.1
0.6 HC
0.6 HC
0.6 HC
1.2 HC
0.6 HC
1.2 HC
0
0
0
0
0
0
0
0
0
0
0
0
0
Oil
thick.
mm
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
14
-------
Notes— Opt. A, B, C, D, or E designates the best initial estimate of what
that optimum setting should be.
Opt. A+ = 0.15 means to increase the setting by 0.15
Opt. A- = 0.15 means to decrease the setting by 0.15
Opt. A* = designates the optimum value found via testing.
15
-------
CO
01
0
u>
O
w
o
u
en
u
H
H
H
1400 r
1300 -
1200
1100.
1000
900
800
700
600
Sunvis 1650 Oil Properties-OHMSETT Measurements
837 x 10~6m2/s @ 21.7°C Kinematic Viscosity
0.881 Specific Gravity
32.5 x 10-6N/m2 Surface Tension*
19.5 x 10~6N/m2 Interfacial Tension*
*With OHMSETT water, salinity 16 ppt
_L
I I
15 16 17 18 19 20 21 22 23 24 25 26
TEMPERATURE (%C)
Figure 9. Graph of kinematic viscosity as a function of temperature for Sunvis 1650 oil.
-------
OIL STORAGE AREA
OFFICES/
LAB SHOP
FACILITIES
]) Test Director
<->v
3) Test Engineer
^ Oil Distribution
<~s
Jy Bridge/Wave Op.
—>.
5) Skimmer Op.
~£\ Sample Collector
j) Photographies
Video Camera
Data Analysis
Chemistry Lab
Filter/VDU Gen.
CONTROL TOWER
(A)
BEACH
£
VIDEO BRIDGE
X
/
AUXILIARY BRIDGE'
X^-v'_X_/ XXX X X X ^ X
a
MARCO
-SKIMMER
-UW VIDEO
BELT
TOVn.INES AND
BO_QM_SKJJ
o
a
OIL DISTRIBUTION
SYSTEM
WAVE FLAPS
T
Figure 10. Test tank layout of MARCO V.
17
-------
bottom. Laboratory analysis of each fraction gave the actual oil content
of the fluid recovered by the skimmer. From this total sample came data
for the recovery rate and throughput efficiency.
The analysis procedure also measured the degree of emulsification
caused by the belt and oil laydown. To determine emulsification properties,
percent water was measured at various centrifuging times to produce a
curve of percent water vs. centrifuge time. Centrifuging continued
until the water measurement did not change. This point on the curve was
used to find total water and total oil contents in the recovered fluid.
Oil was distributed from the main bridge onto the water into the
mouth of the two V-booms which angled back to the skimmer's mouth. Usually,
100% of the oil was encountered by the skimmer.
18
-------
SECTION 6
RESULTS AND DISCUSSION
The highest oil recovery rate in calm water was 6.6 x 10~3m3/s at
a tow speed of 1.03 m/s. Recovery rate increased with speed because
belt capacity was never reached during these tests. Data obtained in
the OHMSETT test program with a 3 mm thick oil slick are plotted together
with curves of maximum (oil-saturated belt) oil capacity from MARCO
Pollution Control in Figure 11. Both data points are well below the
maximums as shown by the curves.
Increased tow speed and wave severity both resulted in decreased
throughput efficiency. The maximum observed efficiency of 99% occurred
in calm water at a tow speed of 0.51 m/s. Increased speed caused oil
to be washed out of the belt in calm water, lowering throughput efficiency
up to 31%. Oil droplets washed out of the belt were ejected from the
skimmer by the induction pump (Figure 12). Waves lowered calm-water
efficiency 18 to 59% at comparable tow speeds in the 0.6 m HC wave and
40% in the 1.2 m HC. This reduction results from skimmer motion in wave
conditions, coupled with waves throwing oil over the booms used to
funnel it into the skimmer.
Increased tow speed caused no effect on the average recovery efficiency
of 78% in calm water. This result is comparable with those determined
by MARCO Pollution Control (Figure 13). Harbor chop waves decreased
recovery efficiency at all speeds with declines of 50% observed at
higher speeds and also with the higher wave condition. HC wave test
recovery rates dropped by 20 to 58% compared to the calm water results.
Again, causes were pitching of the skimmer in the waves and splashing of
oil over the funnel booms.
Results are summarized in Table 3. The full matrix of tests
actually conducted is given in Appendix C, Table C-l.
19
-------
00
25.2
18.9
12.6
6.3
0
0.001
BASIS: 4 Pores Per cm Material
Belt Saturation
2.54 cm thick x 91.4 cm wide Belt
1.5 m/s
0.6 m/s
0.01
OIL VISCOSITY - x 10 3m
3_2
0 = Recovery rate (OHMSETT Testing) @ 1.54 m/s
O = Recovery rate (OHMSETT Testing) @ 0.51 m/s
both with 3 mm thick slick
Figure 11. Oil recovery for the MARCO Class V.
20
-------
Figure 12. Oil droplets (850 x 10-6nr/s Kinematic Viscosity) washed from
the filterbelt being ejected from the skimmer by the induction
pump.
21
-------
% OIL
10
20
40
60
80
0.1
X!
M
en
O
u
CO
M
0.01
0.001
100
BASIS: 4 Pores per cm
Material Belt
Saturation
100
80
40
20
60
% WATER
0 = OHMSETT test data average in calm water
Figure 13. Water retention characteristics (recovery
efficiency) of filterbelt.
22
-------
TABLE 3. SUMMARY OF RESULTS
Wave Calm 0.6 m HC 1.2 m HC
Tow Speed m/s 0.51 1.03 1.54 0.51 1.03 1.54 0.51 1.03 1.54
Recovery
Efficiency % 78.1 77.9 76.8 73.6 50.8 36.8 35.4 34.2
w Recovery
Rate
xlO~3m3 Is 3.7 6.6
Throughput
Efficiency % 98.5 92.9
5.9 3.0 3.3 3.5 2.8
67.9 76.1 44.6 27.7 59.6 39.8
Recovery Efficiency = Oil Recovered (m3)
Total Fluid Recovered (m3)
Recovery Rate = Oil Recovered (m3)
Total Recovery Time (sec)
Throughput Efficiency = Oil Recovered (m3) x 10Q
Oil Distributed (m3)
-------
BIBLIOGRAPHY
1. Norton, R.W. and D.W. Lerch. An Oil Recovery System for San Francisco
Bay Area. In: Proceedings of the Conference on Prevention and
Control of Oil Pollution. American Petroleum Institute, Washington,
B.C., 1975. pp. 317-322.
2. Smith, F.M. Developing a Total Oil Spill Cleanup Capability in the
San Franciso Bay Area. In: Proceedings of the Joint Conference on
Prevention and Control of Oil Pollution. American Petroleum
Institute, Washington, D.C., 1973. pp. 21-26.
24
-------
APPENDIX A
OHMSETT DESCRIPTION
United States Environmental Protection Agency
Figure A-l. Photograph of OHMSETT.
The U.S. Environmental Protection Agency is operating an Oil and
Hazardous Materials Simulated Environmental Test Tank (OHMSETT) located
in Leonardo, New Jersey. This facility provides an environmentally safe
place to conduct testing and development of devices and techniques for
the control of oil and hazardous materials spills.
The primary feature of the facility is a pile-supported, concrete
tank with a water surface 203.3-m long by 19.8-m wide and with a depth
of 2.44 m. The tank can be filled with either fresh or salt water. The
tank is spanned by a towing bridge with a capability of towing loads up
to 15422.4 kg at speeds to 3.05 m/s for a duration of 45 seconds.
Slower speeds yield longer test runs. The towing bridge is equipped to
lay oil on the surface of the water several feet ahead of the device
being tested, such that reproducible thicknesses and widths of oil
slicks can be achieved with minimum interference by wind.
25
-------
The principle systems of the tank include a wave generator and
beach, and a filter system. The wave generator and absorber beach have
capabilities of producing minimum reflection waves to 0.61-m high and
24.38-m long, as well as a series of reflecting, complex waves meant to
simulate the water surface of a harbor or estuary. The water is clarified
by recirculation through a 1.26 m3/s diatomaceous earth filter system to
permit underwater photography and video imagery, and to remove the
hydrocarbons that enter the tank water as a result of testing. The
towing bridge has a built in skimming board which can move oil on to the
North end of the tank for cleanup and recycling.
When the tank must be emptied for maintenance purposes, the entire
water volume 9842 m3 is filtered and treated until it meets all applicable
State and Federal water quality standards before being discharged.
Additional specialized equipment will be used whenever hazardous materials
are used for tests. One such device is a trailer-mounted carbon treatment
unit which is available for removal of organic materials from the water.
Tests at the facility are supported from a 650 square meter building
adjacent to the tank. This building houses offices, a quality control
laboratory (which is very important since test oils 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 contractor,
Mason & Hanger-Silas Mason Co., Inc., provides a staff of twelve multi-
disciplinary personnel. The U.S. Environmental Protection Agency
provides expertise in the area of spill control technology, and overall
project direction.
For additional information, contact:
OHMSETT Project Officer
U.S. Environmental Protection Agency
Research & Development
Edison, New Jersey 08817
Phone: 201-321-6631
26
-------
APPENDIX B
FILTERBELT PRINCIPLES
The characteristics of the filterbelt material are all-important in
the oil pick-up process. If both water and oil can, by virtue of belt
characteristics, flow into the belt at the same rate, the separation of
the two can occur in or on the belt.
The flow-through filterbelt principle developed by the Martin Marietta
Corporation Research Department solves the problem of allowing relatively
free water flow but capturing and removing oil. In this system, open
cell polyurethane foam is used which has relatively large cell dimensions.
A number of considerations were involved in selecting the pore dimensions:
a) Flow-Through Ability
The pores should be large for minimum resistance to the flow
of water through the belt so that the actual encounter of oil
carried by the water to the belt is maximized.
b) Water Retention
The pores should be large enough to permit water to drain
completely and rapidly from the foam after removal from the
water surface. The pore size is very important in this
regard. If the pore (which is oleophilic and hydrophobic) is
too small, droplets of water will be held up by water surface
tension forces, and a large volume of water is retained in the
foam. A droplet of water cannot stably reside in foam of
pore size larger than 0.25 cm, and minimum water pickup is
achieved. All MARCO skimmers provide for onboard gravity
oil/water separation and water decanting which further reduces
the actual water content in the recovered mixture. This water
is pumped overboard ahead of the operating filterbelt where
entrained oil is recaptured.
c) Oil Retention
Pore size is related to oil retention capability as well as to
water retention, even though the physical mechanisms by which
each is held are different. A water droplet cannot fall through
a small hydrophobic pore, but oil adheres to the oleophilic
material by wetting. The significant factor to consider, there-
27
-------
fore, is maximizing oil retention and minimizing water retention.
However, as the oil viscosity increases, the oil begins to be
transported on the surface of the filterbelt rather than through-
out the belt and recovery ratios may vary considerably.
Presenting Spill Oil to the Filterbelt
The MARCO filterbelt conveyor selectively lifts spilled oil off the
surface of waves or calm water. Collected oil and associated debris are
carried via the conveyor system to segregated storage onboard MARCO oil
spill recovery vessels.
Inboard hull shapes and fairings of MARCO skimming vessels are shaped
to provide a smooth flow of spilled oil and water to the pickup conveyor.
The flow of spilled oil to the MARCO collection conveyor is caused by the
forward motion of the skimmer vessels and a flow induction propeller(s)
located behind the oil conveyor just below the surface. Porosity of the
belt plus the flow from the induction pump is used to reduce/eliminate
the frontal pressure wave caused by an advancing oil recovery system,
by causing the water, under the spilled oil, to flow through the oil
collection belt.
High Viscosity Oil Recovery Considerations
Viscous semi-solid oil lays on the surface of the MARCO filterbelt.
This oil is most effectively removed from the filterbelt surface by the
shearing or stripping action of a "Doctor Blade" addressed against the
filterbelt at the head roller. The "doctor blade" is a spring tensioned
assembly which is adjustable for penetration into the filterbelt surface
or the blade may be quickly raised out-of-position when not required.
Light oils that flow as true liquids are pressed from the 1" thick
filterbelt by a tensioned squeeze roller. When operating in a spill
with very viscous oils, the polyurethane foam filterbelt can be replaced
with the MARCO Bunkerbelt. The Bunkerbelt is an open weave, reinforced
belt which transports the oil, "conveyor" fashion, on the surface of the
belt. This belt, because of its very porous nature, enables the induction
pump to produce a very vigorous flow to the belt. This very vigorous flow
is important when processing the heavy, viscous oils, since these oils
do not flow easily. The continuous flow of water under the oil helps to
collect and transport the oil to the belt, where it can be lifted out of
the water.
28
-------
APPENDIX C
DATA AND GRAPHICS
Data presented was obtained during testing of the MARCO Class V and
includes such variables as:
Independent Variables Dependent Variables
Test Number Recovery Rate
Oil Type and Properties Throughput Efficiency
Ambient Conditions Recovery Efficiency
Oil Distribution Rate
Slick Thickness
Wave Condition
Tow Speed
Skimmer Equipment Settings
29
-------
TABLE C-l. TEST RESULTS MARCO CLASS V OCEAN SKIMMER
Ul
i
9/28
9/28
9/28
9/28
9/29
9/29
9/29
9/29
9/29
9/29
9/29
9/30
HH
H-
0929
1058
11,22
1U57
08U1
0928
101,9
1130
1355
1U18
11411
1100
ce
Ul
OQ
jr-
3
Z
CO
Ul
1
2
1R
2R
U
1A
8
9
10
11
12
15
TEST FLUID PROPERTIES
0
LU
Q.
Sun
1650
Sun
1650
Sun
1650
Sun
1650
Sun
1650
Sun
1650
Sun
1650
Sun
1650
Sun
1650
Sun
1650
Sun
1650
Sun
1650
TEMPERATURE
°C
21.7
21.7
21.7
21.7
21.7
21.7
23.9
23.9
23-9
23.9
23.9
23.9
in
CO to
O 1
0 0
CO •—
> X
837
837
837
837
837
837
738
738
738
738
738
738
0
i— i
CO
Ul Z
U- O
o: «—
Z3
CO X
32.5
32.5
32.5
32.5
32.5
32.5
31.7
31.7
31.7
31.7
31.7
31.7
INTERFACIAL
x 10-3N/m
19-5
19-5
19.5
19.5
19-5
19.5
23.1
23.1
23.1
23.1
23.1
23.1
o
>-« >-
li-l-
l—l HH
as
a.2
co us
0.881
0.881
0.881
0.881
0.881
0.881
0.880
0.880
0.880
0.880
0.880
0.880
AMBIENT
CONDITIONS
AIR TEMPERATURE
°C
15.5
17.2
19.5
21.1
11.1
12.8
16.1
16.7
20.0
20.0
20.0
16.1
a
LU
LU
a.
CO
a
5.8
3.6
2.2
2.7
3.1
1.8
2.2
3.6
1,.5
3.1
3-1
0.0
WIND
DIRECTION
E
E
E
E
E
E
E
E
E
E
E
E
SLICK
PARAMETERS
DISTRIBUTION
RATE x 10-3m3/s
5.1
5.0
1,.8
5-14
5-0
5.o
7.9
9.1
10.7
11.0
11.0
13.3
SLICK THICKNESS
mm
11.0
10.7
10.1,
11.6
10.8
10.9
8.5
9.8
11.6
11.9
11.8
9-6
WAVE
CONDITION
CALM
CALM
CALM
CALM
CALM
CALM
CALM
CALM
CALM
CALM
CALM
CALM
o
LU
Ul
a.
co
0.51
0.51
0.51
0.51
0.51
0.51
1.03
1.03
1.03
1.03
1.03
1.514
LU
K- 1
h-
CO
LU
1—
Ul
1 .
LU U
i— aj
co in
210
135
45
70
8?
90
72
97
66
TEST EQUIP.
SETTINGS
0
LU
Ul
Q.
CO
1—
— 1 Ul
LU -~.
co E
0.1,6
0.1,6
0.61,
1.22
0.91
0.91
1.25
1.16
0.91,
1.22
1.22
0.91
Q-
g
a
CM
LU E
a: -~~.
ID Z.
COm
CO O
LU •—
Of.
o. x
31,. 14
314.1,
3U.14
314.1,
1,8.2
314-1,
51.7
51.7
51.7
68.9
31,. 1,
68.9
PERFORMANCE
CHARACTERISTICS
LU
Su,
-s.
cc E
LU«
1°
LU
ce x
2.38
3.73
3.1,6
6.1,9
5-72
6.614
7.91
6.00
5.32
THROUGHPUT EFF.
%
98.5
81.5
78.6
77.8
83.6
88.7
95-9
89.1
92.9
86.0
88.1,
1,5.3
u.
LU
LU
an
LU
o
<_)
LU
a: »«
78.1
60.0
51.6
142.14
514.6
52.7
59-3
62.7
77-9
68.1
61.0
72.8
(Continued)
-------
TABLE C-l. (Continued)
LU
§
9/30
9/30
9/30
9/30
10/1
10/1
10/1
10/1
LU
t-4
1135
1322
1U08
1500
0900
09U6
1102
1326
eg
LU
1
z
ft
LU
15R
16
16R
25
26
27
26
29
TEST FLUID PROPERTIES
_i
0
LU
QL
£
Sun
1650
Sun
1650
Sun
1650
Sun
1650
Sun
1650
Sun
1650
Sun
1650
Sun
1650
TEMPERATURE
°C
23.9
23.9
23.9
23.9
23.9
23.9
23-9
23.9
ui
££
H-« E
«/Jl»
S£,
to i—
»— 1
>• X
738
738
738
738
738
738
738
738
o
»— *
to
LU
1- E
LUZ-
O"
p
to x
31.7
31.7
31.7
31.7
31.7
31.7
31.7
31.7
INTERFACIAL
x 10-3N/m
23.1
23.1
23.1
23.1
23.1
23.1
23.1
23-1
SPECIFIC
GRAVITY
0.880
0.880
0.880
0.880
0.880
0.880
0.880
0.880
AMBIENT
CONDITIONS
AIR TEMPERATURE
°C
16.7
15-5
13.9
13-3
15-5
15.5
15.5
15-5
o
LU
LU
d.
l/J
o
IT UI
•— < —
= E
0.0
0.0
tu
0.1,
7.6
6.7
5.8
6.3
WIND
DIRECTION
SE
SW
SE
SE
. SW
SW
SW
SW
SLICK
PARAMETERS
in
--»
m
O1*1
>-! I
h- O
=>•—
m
5X
ft£
SS
12.2
.6.3
12.7
6.1
9.9
13.6
U.9
6.9
SLICK THICKNESS
mm
8.8
l».5
9.1
13.1
10.7
9-7
10.5
7.5
WAVE
CONDITION
CALM
CALM
CALM
0.6m
HC
0.6m
HC
0.6m
HC
1.2m
HC
1.2m
HC
a
LU
LU
a.
to
~ -
a
LU O
1— 0>
to u>
71
60
7?
186
80
65
60
TEST EQUIP.
SETTINGS
a
LU
LU
a.
to
t-
_J VI
LU -«»
CO E
0.91
0.91
0.91
0.61)
0.91
0.61
0.61
0.61-
0.91
a_
o
ex
a
N
§1
to«
to o
LU i—
a:
o. x
68.9
86.1
86.1
3ii.li
51.7
68.9
3h.h
75-8
PERFORMANCE
CHARACTERISTICS
LU
iM
•^.
>-r>
CC E
LUn
> 1
O 0
to •—
LU
Ct X
6.57
5-2U
5.79
2.97
3.31
3.h6
2.76
THROUGHPUT EFF.
%
63.5
83.1
57.1
76.1
fcli.6
27.7
59.6
39.8
RECOVERY EFF.
2
77.8
77.3
75-5
73.6
50.8
36.8
35.h
3l).2
-------
LO
2R
4R
9 10 11 12
TEST NUMBER
15 15R 16 16R
Figure C-l. Oil Recovery Rate for MARCO CLASS V Ocean Skimmer in calm water
at various equipment settings with 3 mm thick slick of Sunvis
1650 oil.
-------
CO
co
5.0 -
w 4.0
2
O
O
ri
o
3.0
2.0
1.0
0.51 m/s
I
I
25
WAVE CONDITION
0.6 m HC
1.03 m/s
I
TOW SPEED
1.54 m/s
I
1
26
27
1.2 m HC
I
1.03 m/s
29
TEST NUMBER
Figure C-2. Oil Recovery Rate for MARCO Class V Ocean Skimmer in 0.6m and 1.2 m
Harbor Chops at optimum equipment settings with 3 mm thick slick of
Sunvis 1650 oil.
-------
CO
100
90
x~\
v»x
i 80
H 70
H
w 60
1 50
8 40
30
20
10
0.51 m/s
I
TOW SPEED
1.03
I
1.54 m/s
I I
1R 2R
4R 8 9 10 11 12
TEST NUMBER
15 15R 16 16R
Figure C-3. Recovery Efficiency for MARCO Class V Ocean Skimmer in calm water at various
equipment settings with 3 mm thick slick of Sunvis 1650 oil.
-------
Ui
90
80
/~\
&s
•***
B 70
60
w 50
8
40
30
20
10
I
0.51 m/s
I
r
25
WAVE CONDITION
0.6 m HC
I
1.03 m/s
r—«—
TOW SPEED
1.54 m/s
r
1.2 m HC
I
I I
0.51 m/s 1.03 m/s
I I
r
i r
26 27
TEST NUMBER
28
29
Figure C-4. Recovery Efficiency for MARCO Class V Ocean Skimmer in 0.6 m and 1.2 m
Harbor Chop at optimum equipment settings with 3 mm thick slick of
Sunvis 1650 oil.
-------
co
Oi
100 —
y 7n —
H
u
H
w
10 —
TOW SPEED
1.03 m/s
1.54 m/s
i
1R 2R
8 9 10 11 12
TEST NUMBER
15 15R 16 16R
Figure C-5. .Throughput Efficiency for MARCO Class V Ocean Skimmer in calm water at
various equipment settings with 3 mm thick slick of Sunvis 1650 oil.
-------
9CK
~ 80
B 70
u 60
w
50
I 40
1
S 30
20
10
I
0.51 m/s
I
25
WAVE CONDITION
0.6 m HC
I
1.03 m/s
I I
I
TOW SPEED
1.54 m/s
I
1.2 m HC
I
26 27
TEST NUMBER
0.51 m?fs
I I
28
1.03 m/s
29
Figure C-6. Throughput Efficiency for MARCO Class V Ocean Skimmer in 0.6 m and 1.2 m
Harbor Chops at optimum equipment settings with 3 mm thick slick of Sunvis
1650 oil.
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1 REPORT NO.
EPA-600/2-78-093
4. Tl TLE AND SUBTITLE
2.
OHMSETT "High Seas" Performance Testing:
V Oil Skimmer
MARCO Class
7 AUTHOR(S)
G.F. Smith and W.E. McCracken
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Mason & Hanger-Silas Mason Co., Inc.
P. 0. Box 117
Leonardo, New Jersey 07737
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laboratory ^-Cin., OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
3. RECIPIENT'S ACCESSION-NO.
6. REPORT DATE
May 1978 issuing date
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
1BB610
11. CONTRACT/GRANT NO.
68-03-0490
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A MARCO Class V oil skimmer was tested at the U.S. Environmental
Protection Agency's OHMSETT facility to determine the device's "high
seas" performance characteristics. Performance data was obtained for
several simulated offshore wave conditions at various collection speeds.
Skimmer efficiency was determined at various belt speeds and induction
pump rates in order to define optimum skimmer settings and to better
define oil/water spearator needs. This report of testing done under
Contract No. 68-03-0490, Job Order No. 22, by Mason & Hanger-Silas
Mason Co., Inc., for the U.S. Environmental Protection Agency covers
the period September 27, 1976, to October 1, 1976, with work completed
January 14, 1977.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Performance tests
Skimmers
Water pollution
Oils
b.IDENTIFIERS/OPEN ENDED TERMS
Spilled oil cleanup
c. COSATI Field/Group
68D
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
•••^i^^^M
EPA Form 2220-1 (9-73)
19. SECURITY CLASS
UNCLASSIFIED
eport)
46
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
38
*U.l GOVBWMEHTPHHTIIBOfFICLBTS—757-140/6831
------- |