WATER POLLUTION CONTROL RESEARCH SERIES 15080 FWN 07/71
RECOVERY of FLOATING OIL
ROTATING DISK TYPE SKIMMER
ENVIRONMENTAL PROTECTION AGENCY WATER QUALITY OFFICE
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WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Series describes
the results and progress in the control and abatement
of pollution in our Naion's waters. They provide a
central source of information on the research, develop-
ment, and demonstration activities in the Water Quality
Office, Environmental Protection Agency, through inhouse
research and grants and contracts with Federal, State,
and local agencies, research institutions, and industrial
organizations.
Inquiries pertaining to Water Pollution Control Research
Reports should be directed to the Head, Project Reports
System, Office of Research and Development, Water Quality
Office, Environmental Protection Agency, Washington, D.C. 20242,
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RECOVERY OF FLOATING OIL
ROTATING DISK TYPE SKIMMER
by
Atlantic Research Systems Division
Marine Systems
A Division of the Susquehanna Corporation
Costa Mesa, California 92626
for the
WATER QUALITY OFFICE
ENVIRONMENTAL PROTECTION AGENCY
Project #15080 FWN
Contract #14-12-883
July 1971
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.25
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EPA Review Notice
This report has been reviewed by the Water
Quality Office, EPA, and approved for publication
Approval does not signify that the contents
necessarily reflect the views and policies of
the Environmental Protection Agency, nor does
mention of trade names or commercial products
constitute endorsement or recommendation for
use.
11
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ABSTRACT
Laboratory tests of disc materials in oils ranging from light diesel
to Bunker 'C' indicated that aluminum was the best overall. Experimental
tests on model discs in still water established baseline performance
data and understanding of scaling effects. Established that oil
starvation between discs is a problem, but that percentage of water in
recovered oil is less than 2% except for Bunker 'C'oil, and other
oils in 2mm thickness slicks. Experimental tests of multiple discs in
a towing basin established the effects of current and disc spacing,
and showed that the rotational velocity vector in the fluid should be
in the same direction as the current flow. Non-breaking waves have
little effect on oil pick-up rate. The design method developed by
comparison between theoretical analysis and experimental data shows
that the overall size of the disc unit would be 7 ft. diameter by
12 ft. for recovery of 50,000 gallons per hour.
This report was submitted in fulfillment of Project Number 15080FWN,
Contract 14-12-883, under the Cpartial) sponsorship of the Water
Quality Office, Environmental Protection Agency.
111
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TABLE OF CONTENTS
Section Page
I CONCLUSIONS 1
II RECOMMENDATIONS 3
III INTRODUCTION 5
IV EXPERIMENTAL PROGRAM 7
Oil Recovery Material Evaluation 1
Static Tests in a 10-Foot Trough 3
Tests in a 300-Foot Towing Basin 8
V DESCRIPTION OF TEST APPARATUS 11
VI TEST PROCEDURES 19
VII TEST RESULTS 25
VIII TECHNICAL DISCUSSION 79
EX THEORETICAL MODEL AND COMPARISON WITH
EXPERIMENTAL RESULTS 83
X DESIGN APPROACH 105
Performance Envelopes for the Disk System 105
Design Solutions 113
Operational Recommendations 114
XI REFERENCES 123
XII SYMBOLS 125
XIII APPENDICES 127
v
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LIST OF ILLUSTRATIONS
Figure
No.
1 Oil Recovery Test Set-Up in 10 Foot Trough 12
2 Oil Recovery Test Set-Up in 10 Foot Trough 13
3 Single Disk Assembly in 10-Foot Trough ........ 14
4 Test Set-Up in 300 Foot Two Basin 16
5 Multi-Disk Tow Tank Test Model 17
6 Multi-Disk Test Configuration 22
7 Wiper Blade Assembly 24
8 Dipping Tests - Oil Pickup on Aluminum 25
9 Dipping Tests - Oil Percentage Pickup on Aluminum 27
10 Zero Current Oil Recovery Tests 30
11 Zero Current Oil Recovery Tests 31
12 Zero Current Oil Recovery Tests 32
13 Zero Current Oil Recovery Tests - Effect of Disk Diameter and
Depth on Oil Pickup 33
14 Zero Current Oil Recovery Tests 34
15 Zero Current Oil Recovery Tests 35
16 Zero Current Oil Recovery Tests 36
17 Zero Current Oil Recovery Tests 37
18 Zero Current Oil Recovery Tests 39
19 Zero Current Oil Recovery Tests 40
20 Zero Current Oil Recovery Tests 41
21 Zero Current Oil Recovery Tests 42
22 Zero Current Oil Recovery Tests . - 43
23 Zero Current Oil Recovery Tests 44
24 Zero Current Oil Recovery Tests 45
25 Zero Current Oil Recovery Tests 45
26 Zero Current Oil Recovery Tests 47
27 Zero Current Oil Recovery Tests 49
28 Zero Current Oil Recovery Tests 50
29 Zero Current Oil Recovery Tests 51
30 Zero Current Oil Recovery Tests 52
31 Zero Current Oil Recovery Tests 53
32 Zero Current Oil Recovery Tests 54
33 Zero Current Oil Recovery Tests 55
34 Zero Current Oil Recovery Tests 56
35 Oil Recovery Tests Smooth Water - Current Conditions ... 60
36 Oil Recovery Tests Smooth Water - Current Conditions ... 61
37 Oil Recovery Tests - Current Conditions 62
38 Oil Recovery Tests - Current Conditions 63
39 Oil Recovery Tests - Current Conditions 64
vi
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LIST OF ILLUSTRATIONS (Continued)
Figure
No.
40 Oil Recovery Tests - Current Conditions 65
41 Oil Recovery Tests - Current Conditions 66
42 Oil Recovery Tests - Current Conditions 67
43 Oil Recovery Tests - Current Conditions 68
44 Oil Recovery Tests - Current Conditions 69
45 Oil Recovery Tests - Current Conditions 70
46 Oil Recovery Tests - Current Conditions 71
47 Oil Recovery Tests - Current Conditions 72
48 Oil Recovery Tests - Current Conditions 73
49 Oil Recovery Tests - Current Conditions 74
50 Oil Recovery Tests - Wave & Current Conditions 75
51 Oil Recovery Tests - Wave & Current Conditions 76
52 Oil Recovery Tests - Current Conditions 77
53 Oil Recovery Tests - Current Conditions 78
54 Disk Oil Recovery Configuration 84
55 Oil Boundary-Layer Formation on Disk 84
56 Equilibrium of Forces Acting on Boundary-Layer 85
57 Boundary Conditions 87
58 Oil Fillet 88
59 Theoretical Model Results 94
60 Comparison of Theory with Experiment - No Current .... 98
61 Comparison of Theory with Experiment - With Current .... 99
62 Effect of Current on Collection at Constant Slick Thickness . . 100
63 Effect of Current on Collection at Constant Slick Thickness -
Thin Slick 102
64 Boundaries Between Disks 103
65 Model Disk 106
66 Oil Recovery System - Design Parameters 110
67 Oil Recovery System - Design Parameters Ill
68 Oil Recovery System - Design Parameters 112
69 Oil Recovery System - Design Parameters 115
70 Oil Recovery System - Design Parameters 116
71 Oil Recovery System - Design Parameters 117
72 Oil Recovery System - Design Parameters 118
73 Oil Recovery System - Design Parameters 119
74 Disk with Deflectors 120
75 System with Herding Booms 121
76 System with Anchored Booms 121
VII
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LIST OF TABLES
1 Case 1: Designs of Full Scale Systems for Thick Slick . . . . 113
2 Case 2: Designs of Full Scale Systems for Thin Slick .... 114
viii
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SECTION I
CONCLUSIONS
The most important conclusions resulting from this study are:
1. The recovery of 50,000 gallons of oil per hour using a series of
powered disks is feasible and practical. The overall size of the disk
unit is approximately 7 ft. diameter x 12 ft. long.
2. Disks can pick up oil spread as thinly as 1.5mm in thickness. How-
ever, pickup efficiency and effectiveness is greatly improved with
increased thickness. Refer to Figure 17, 23 and 32.
3. The disks can effectively be used for the pickup of light diesel as well
as Bunker 'C' oil.
4. Disk pickup effectiveness is limited by starvation Starvation is the
reduction of oil in the region adjacent to the disk due to insufficient
feed-in or spreading of the oil.
5. Herding of the oil with the use of booms or other types of barriers
will improve pickup effectiveness because herding increases oil thick-
ness at the disks and eliminates disk starvation. Current, whether
natural or caused by towing the disk unit through the oil, will also
increase oil thickness at the disks and help to eliminate disk starvation.
6. Tests carried out in waves in both the 10-foot trough and the model
towing basin showed that the disk system is very insensitive to waves
with regard to oil pickup. In fact, there was a tendency to pick up more
oil at a given time in waves which were not choppy enough to cause oil
entrainment with the water.
The disks must be large enough in diameter, and their motions relative to the
sea surface must be modest enough that the disks are never immersed beyond
the lower half of the axle, or that they come out of the fluid surface.
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One advantage of the disk system in waves is that it does not disturb the oil
surface as would a rotating drum; this was also demonstrated by the model
tests.
Disturbing the oil causes entrainment and transfer of oil to greater than pickup
depths, thus reducing pickup effectiveness.
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SECTION II
RECOMMENDATIONS
It has been shown that a simple multiple disk unit can be designed with a prac-
tical sizing and with modest power requirements, to pick up the required
50,000 gallons per hour of oil types ranging from Bunker 'C' to light diesel.
This can be done in 5-foot seas combined with 2 knots current and does not
require a complicated disk section, expensive material, or high rotational
speeds. Water content should be well under the 10% or less requirement;
therefore, a separator may not be necessary.
The total recovery system is expected to consist of the disk unit, a herding
barrier, support platform and the storage unit. The disk recovery effective-
ness is dependent upon the interactions of these units and although the prelim-
inary analyses indicate that these interactions are minimal, further experimental
verification, preferably in full scale, is recommended.
In addition, further study of anti-starvation deflector plates between the disks
should be performed. Again this evaluation should be conducted in near full
scale.
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SECTION IE
INTRODUCTION
A study to determine the effectiveness of rotating disks for the recovery of oil
in the open ocean was conducted for the Department of Interior, Federal Water
Quality Administration. This report describes the results of this study.
Rotating disks for oil recovery afford the following potential advantages:
1. Removal of oil from the sea surface while collecting a minimum
amount of residual water, thus reducing the need for subsequent
oil-water separation.
2. Minimum sensitivity to wave forces which reduces stresses in the
system.
3. Minimum sensitivity to debris and other foreign objects.
Oil harvesting units presently available for open ocean use are limited by their
low recovery capacity, high air/water content and/or rapid loss of efficiency in
wind and waves. A successful recovery system must have a high recovery rate
even in a relatively severe sea condition, minimum sensitivity to wave forces,
and be economical and easily employed.
A recovery system used successfully in limited sea states is the rotating drum.
This system utilizes the principle that the oil will readily adhere to the drum
surface, from which it is recovered with a wiper. It is capable of recovering
the oil with viscosities ranging from light diesel to Bunker 'C' grade oil. The
low water content of the recovered oil eliminates any need for an oil-water
separator or for discharging the entrained water overboard.
The rotating disk system utilizes this principle of recovery, but because it
increases the wetted surface area, it has a potential for greater recovery
capacity.
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The evaluation program consisted of:
1. Laboratory tests of several disk material candidates.
2. Experimental tests of the disks in still water to establish baseline
performance data and to determine scaling effects.
3. Experimental tests of the disks in the tow tank in current and waves.
4. Comparison between theoretical analysis and experimental data and
the derivation of non-dimensional scaling coefficients.
5. Preliminary sizing recommendation for a disk unit for the recovery
of 50,000 gallons of oil per hour.
The study was made for oil types ranging from light diesel to Bunker 'C' oil.
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SECTION IV
EXPERIMENTAL PROGRAM
The experimental program was divided into three parts:
1. Laboratory dipping tests to determine the best material for oil
pickup.
2. Tests in a 10-foot long trough to establish the scaling laws with
regard to disk diameter, depth of immersion and rotational speed
in a range of oil types and slick thicknesses.
3. Tests in a 300-foot towing basin to find the effects of current and
disk spacing at various rotational speeds on oil pickup rates for
various oil types. Tests were conducted to find the effect of waves
combined with current on pickup rate for one oil type. Tests were
also made for one oil type to determine the best direction of rotation
of the disk relative to the current.
The experimental program was tailored to a theoretical analysis of the
mechanics of oil pickup. Based on the results of the Reference 1 studies, it
was felt that the effects of wind could be adequately covered by considering
wind as an equivalent current; therefore, no wind tests were performed.
OIL RECOVERY MATERIAL EVALUATION
This evaluation was performed to determine suitable materials for recovery
of floating oil. The materials were evaluated for use in oil harvester disk
tests to be performed under the following sections.
Materials were evaluated against a full range of oil varieties (diesel fuel,
Bunker 'C', and crude oil) to determine percentages and quantities of oil and
water retained under controlled conditions.
Additional tests were conducted in mixtures of Bunker 'C1 and diesel fuel
against aluminum to evaluate variations with viscosity.
Eight materials were selected for evaluation: Polypropylene, Polycarbonate,
Polyethylene, Teflon, Neoprene, Aluminum, Stainless Steel, and Mild Steel.
Samples measured 1" x 2" x 1/16" thick untreated. Total surface area for
each sample was determined to be approximately 4.3 square inches.
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STATIC TESTS IN A 10- FOOT TROUGH
This evaluation was performed to determine the effect of various parameters
on the oil pickup rate of a rotating disk. Most of the tests were performed with
a single powered disk of the optimum material which turned out to be aluminum,
as determined by the material evaluation tests, cost analysis, machinability, and
reliability analysis. The oils used were diesel oil, 40-weight motor oil and
Bunker 'C' fuel oil. The parameters which were varied sequencially were disk
diameter, disk immersion depth, disk rotational speed, static oil slick thickness,
and wiper gap. Brief tests in diesel oil investigated the effect on oil pick-up rate
of multiple disks side by side, and also the effect of disk immersion cycling to
simulate waves. Disk diameters ranged from 8 to 18 inches, immersion depths
from 0.5 inches to 6 inches, rotational speeds up to 0.8 revs/sec, slick thick-
nesses from film to 2.5 inches, and wiper gap from 0.025 inches to zero with
rubber wipers, to pressure with rubber wipers for diesel oil pick-up.
Brief tests were conducted in diesel oil with five 18-inch diameter disks spaced
1.5 inches apart, with eight disk sides wiped with positive pressure rubber
wipers. (Note that these tests could only be performed with diesel oil because
of the high rate of oil pickup.) Waves 5 inches by 1.6 sec. period were simu-
lated by disk immersion oscillation.
TESTS IN A 300-FOOT TOWING BASIN
The oil recovery test program was conducted at the General Dynamics Convair
Marine Test Facility model tow basin from 24 September through 2 October
1970. The equipment used in these tests was the multiple disk oil recovery
machine, with 18-inch diameter disks. The test section was 100 feet long by
2 feet wide by 4 feet deep, open at the bottom. The test program was divided
into a number of sections; in each section, one or more of the test parameters
were varied. Most tests used 40-weight motor oil. The first tests involved
running a battery of five disks at 1.5 inch spacing with disks rotating both with
and against the current to determine the best operating condition for all subse-
quent tests.
Tests were then conducted with variations of disk immersion, oil thickness and
disk rotational speed up to 2 rps, in current speeds up to 3 knots in smooth
water. Further tests were made similar to those above with two other disk
spacings. All of these test runs used 40-weight motor oil.
Tests were run in regular waves combined with current in one oil thickness
and two disk immersion depths, using 40-weight oil.
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The last thirty test runs of the test program were made with Bunker 'C' oil
one inch thick, at a disk spacing of 1-1/2 inches. The test fixture could not
handle the quantity of oil and the disk drive motor could not maintain a con-
stant speed during a run with the original multiple disk machine; for this
reason, the data obtained in the first four runs is suspect. The test setup
was then modified, but with only partial success. Tests with Bunker 'CT oil
were discontinued. No tests of this type were performed with diesel oil.
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SECTION V
DESCRIPTION OF TEST APPARATUS
MATERIAL DIPPING TESTS
1. Scale, microgram Mettler, type H6T dig Cap 160g
2. Desiccator Pyrex: Sulphuric Acid desiccant
3. Beaker 1000 m 1
250 m 1
4. Test Specimens Composition perd escription under
1" x 2" x 1/16" experimental program
STATIC TESTS IN A 10 FOOT THROUGH
The test apparatus is shownph otographically in Figures 1, 2 and 3. A water
tight mirror box was inserted in the galvanized steel through so that a view
could be obtained under the oil surface. The aluminum disk was driven via
bicycle gears and chains by a 1/12 H. P. A. C. motor with variable speed
control. A second 1/12 H.P. variable speed motor powered the disk immer-
sion cycling, and was also used to set disk immersion statically. The speed
range of the disk was about 0.3 to 0. 8 r.p. s. Oil wipers were either slots
in an aluminum sheet, with small clearance to the disk; or rubber wipers
with close contact, when using Diesel Oil. The wiped oil was drained into a
sliding container of 1 gallon capacity, which could be removed for draining
into a transparent plastic bucket to permit checking water content of the
sample. A large number of these plastic buckets were kept on hand as
sometimes the samples had to stand for several hours for complete oil-water
separation. Pint graduation marks on the outside of the buckets were used
to check volumes.
Ancillary appartus consisted of accurate weigh scales and a stop watch.
11
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Figure 1. Oil Recovery Test Set-Up in 10 Foot Trough
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Figure 2.
Oil Recovery Test Set-Up in 10 Foot Trough
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Figure 3. Single Disk Assembly in 10 Foot Trough
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TESTS IN A 300 FOOT TOWING BASIN
The test basin is operated by General Dynamics, Convair, in San Diego, and
is described in Ref. 5.
It was completely lined with polyeurythene plastic, and a separate wooden
trough without a bottom was constructed inside of it. The test trough was
100 feet long, by 2 feet wide by 4 feet deep, open at the bottom. A 50 foot
length of one side was made of plexiglass to permit flow visualization and
photography. Figures 4a and 4b show the test set-up. The multiple disk
oil recovery machine is shown in figures 5a and 5b.
The disk machine was mounted on a plywood base-board, which in turn was
attached to the under frame of the tow-basin carriage. The carriage carried
110 volt power for operating the 1/4 H.P- variable speed disk drive motor,
and the 1/12 H.P. disk immersion cycling motor. It also carried power for
cameras and lights. A mirror box, also attached to the tow basin carriage,
enabled the test conductors to see the flow conditions of the under-surface
of the oil, and also to photograph flow phenomena. The 8 foot long box canoe
carried a large mirror set at 45 degrees to the water surface. Observation
was through an eight inch column of water between the plexiglass canoe wall
and the plexiglass through wall. This presented no proglems as the water in
this region was clear of oil. The oil behavior characteristics were recorded
using a still camera taking 2-1/4 x 3-1/4 inch black and white pictures at a
maximum frequency of about one every two seconds. Each print showed
camera number and run number, a clock with a seconds sweep and a counter
for picture-data indentification.
It has originally been intended to collect the oil in a shallow tray at the disks,
and then pump it via a "puddle sucker" up into 5 gallon plastic cans on a
second tow basin carriage. However, preliminary pumping tests showed that
the collected oil is emulsified into a foam, and it would be very difficult to
separate out the water from the collected oil. Therefore, it was decided to
collect the oil in shallow pans at the disk wipers. After the first few test
runs, where all 5 disks were wiped and collected, giving large collection
15
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Figure 4a
Figure 4b
Figure 4. Test Set-Up in 300 Foot Two Basin
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Figure 5a
Figure 5b
Figure 5. Multi-Disk Tow Tank Test Model
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volume, it was decided to wipe all 5 disks, but collect from only the center
one. Depending on the volume collected on one run, collection vessels used
were as follows:
1. Large shallow pan - capacity when dry 1. 244 gallons, and capacity
when primed with 40 wt. oil, 1.169 gallons.
2. Small shallow pan - capacity when dry 0.645 gallons and capacity
when primed with 40 wt. oil, 0. 604 gallons.
3. One-quart size glass fruit jars.
Ancillary apparatus consisted of accurate weight scales and a stop watch.
18
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SECTION VI
TEST PROCEDURES
MATERIAL DIPPING TESTS
The testing was divided into two phases:
Phase I: was conducted with cleaned water wetted samples immersed
in the water and drawn up through the test oil floating on the water sur-
face. Samples were withdrawn at a constant eight second rate per
sample.
Phase II: was conducted with a thin film of test oil applied to the entire
sample surface. Samples were lowered through the test oil slick into
the water and then raised up through the slick again each at the same
eight second rate per sample.
Each material was evaluated in each of the oil types with the exception of
the Bunker 'C'/Diesel mixtures, of which only the aluminum was evaluated.
Water used in all tests was tap water.
Each sample was cleaned prior to each test, placed in an aluminum cup, and
a dry, or film coated, weight measurement was made and recorded. Samples
were then immersed in the oil and an oil plus water measurement made and
recorded. Samples were then placed in a desiccator overnight to draw out
any retained water. Weight measurements were made after the drying cycle
which showed the total oil retained by each sample.
Using the above measurements it was possible to calculate total oil and water
retained by each sample; percentage values were also calculated. This per-
centage of oil pickup is equal to the volume of oil picked up divided by the
total volume of oil and water picked up expressed as a percent.
19
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Oil used in the evaluation was obtained from Terminal Annex, San Pedro;
no special handling was involved, the Bunker TC' being a partially refined
crude oil.
STATIC TESTS IN A 10 FOOT THROUGH
The procedure was to pour oil into the trough to a specified static thickness
which was measured in the mirror box. The aluminum disk was then set to
the required immersion depth using the depth cycling motor. For the 18 inch
diameter disk the wipeable disk settings were up to 6 inches immersion;
for the 12 inch diameter disk up to 4. 5 inches, and for the 8 inch diameter
disk, only up to 1. 5 inches. Disk revolution speed was set and counted
orally using a piece of red tape on the shaft. The 1 gallon capacity collection
pan could be slid on tracks under the wiper tray or drawn back on command.
Time elapsed during a test run was measured by a stop-watch. The collected
oil was poured into a transparent plastic bucket and weighed. After standing
for some hours, the total volume and the volume of water was read on the
graduation marks on the sides of the buckets. Hence percentage water
content was calculated. The only oil for which this could not be done was
the Bunker 'C' which coated the plastic buckets so badly, that the "tarry" oil
had to be poured off until a water surface appeared. The water content was
then estimated.
Optimum wiper gaps turned out to be 0. 025 in. with Bunker 'C' oil, light
contact with rubber wipers for 40 wt. motor oil and pressure contact with
rubber wipers for diesel oil.
The 40 wt. motor oil emulsified rather easily, and the water that went into
the emulsion did not settle out with standing. Excess water did settle out.
Diesel oil emulsified after several days use with a thin slick, but although
the quantities picked up were small, the equipment handled it rather easily.
The Bunker 'C' oil slowly turned to tar and jammed up the equipment after
a few days, making further testing impossible without a complete clean-up.
The drive motor for disk rotation was underpowered, but it was possible to
obtain four distinct speeds up to 0. 8 r.p. s. with a single disk.
20
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Multiple disk test and wave simulation tests were only performed with diesel
oil. The former tests were performed with diesel oil because the equipment
could not have handled the high pick-up rates with the other oils. The wave
simulation tests were performed with diesel oil because this oil coated the
disk very precisely, without local build-ups of oil, even though the actual
oil coatings were very thin. Diesel oil could also be wiped very cleanly,
and specimen weighing was accurate because the plastic buckets could be
emptied completely between use. A total of 246 test runs were made in
August and September 1970.
TESTS IN A 300 FOOT TOWING BASIN
The tests were started on the 5 disk system with all sides wiped and collected,
but the quantity of oil collected was so great that after the initial runs to
find the best direction of disk rotation relative to the current, it was decided
to continue wiping all dsik sides but collect from only the center disks. The
oil from the other disks was carried in individual troughs well aft of the pick-
up area. (See figure 5).
Because the pump could not be used to carry the collected oil away from the
disks due to excessive frothing, good team work was necessary to collect the
oil accurately. The first choice was a large flat pan of volume 1.17 gallons
which had to be completely filled in one run. If there was not enough oil to
completely fill the large pan in one test run, the second choice was a small
flat pan of volume 0. 60 gallons which had to be completely filled, and if there
was not enough oil for this then the oil was collected in a 1 quart glass fruit
jar, which was not necessarily completely filled. A glass jar sample was
used to visually check the water content in the pick-up. If it was apparent
that there was negligible water content, then the pan was filled and no jar
sample was collected for water content. (Note: a jar sample purely for
water content was taken from disks other than the center disk).
For most of the test runs, the disks rolled with the current, and the pan
samples were collected ahead of the disks, while the water content jar
samples were collected aft of the disks. Figure 6 shows the oil collection
system.
21
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WIPER BLADE
ASSEMBLY-
DIRECTION OF
MOTION
2 OUTSIDE DISKS ON EACH SIDE
OIL SPILLED BACK INTO TROUGH WELL
AFT OF DISKS.
DIRECTION OF
MOTION
CENTER DISK WIPER
COLLECTION PAN
CENTER DISK COLLECTED IN PAN
Figure 6. Multi-Disk Test Configuration
22
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The disk wiper system developed during the tests consisted of heavy tape
wipers attached to an aluminum frame work. The wiper blade assembly is
shown in Figure 7. Heavy tape was placed on slots 1, 2, 4, and 5 and slotted
with a knife. Slot 3 in the aluminum was relatively wide and open. Blade 3
was separately wiped and collected.
The procedure on any given test run was as follows:
1. Set diskR.P.S. on controller.
2. Tell carriage operator to go at set speed.
3. When speed was reached, he sounded horn.
4. At that time, pushed collection tray under. Started stop watch and
revolutions count.
5. Pan would fill up as run continued.
6. At time pan started to overflow, engineer would say MARK. Every-
one stopped count. Recorded number of revolutions and time on
stop watch.
7. Machine oil collection was stopped.
8. Carriage slowed and stopped.
9. Lifted back end of collection pan as high as possible.
Under surface black and white photographs were taken on most runs by a
photographer who was present throughout the testing.
The test program was divided into a number of sections. In each section, one
or more of the test parameters was varied. Oil samples were collected each
day for analysis to obtain the physical properties of the oil.
The testing occupied 7-1/2 days of tank time at the end of September 1970,
during which time 216 test runs were made.
23
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WIPER BLADE ASSEMBLY
HEAVY TAPE PLACED ON 1, 2, 4 AND 5 AND SLOTTED
DOWN CENTER ON EACH WITH A KNIFE.
SLOT 3 RELATIVELY WIDE AND OPEN.
BLADE 3 SEPARATELY WIPED AND COLLECTED
Figure 7. Wiper Blade Assembly
24
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SECTION VH
TEST RESULTS
All of the results for the oil dipping test program are listed in Appendix I.
Other test data are not listed. Most of the graphs plotted are for tests in
zero current where the test conditions could be more rigidly controlled than
was possible in the Towing Tank.
The three test programs are separately discussed.
OIL RECOVERY MATERIAL EVALUATION
Tests have shown increasingly larger amounts of oil retained as the viscosity
of the test oil increased, and the drainage from the raised samples decreased.
The oil retained per square inch of material varied from 1 to 2 milligrams of
diesel fuel to 300 milligrams for the Phase I materials. Phase II materials
retained from 10 milligrams to 800 milligrams showing an increase in reten-
tion for the oil-wetted surface samples over the water-wetted samples.
The higher viscosity oils, such as Bunker 'C' or crude, showed less variation
in amounts of oil retained for the various materials (oil or water-wetted). The
heavier oils displaced water when sampled, retaining consistently less than 5
percent water. Lower viscosity oils such as diesel fuel, showed larger vari-
ations with material in the amounts retained. Water retained was also consid-
erably more for some, as high as 50 percent. Oil-wetted samples were more
consistent in the amounts of oil and water retained, polyethylene showing as
the best performer.
No attempt was made to determine optimum pickup rates since only the materials
were being evaluated. For the oil-wetted samples, two passes were made
through the oil slick, only one pass was made for the water-wetted samples.
Aluminum was evaluated in various mixtures of Bunker 'C' and diesel fuel for
its ability to retain oil. Mixtures ranged from 90/10 to 25/75 percent, Bunker
'C'/diesel. Results showed that the higher concentrations of Bunker 'C1 retained
as much as 600 milligrams compared to less than 100 milligrams for the lower
concentrations. See Figures 8 and 9.
25
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600
DIESEL 0
BUNKER C 100
40
I
60
60
40
80
I
20
100
I
0
MIXTURE OF DIESEL AND BUNKER C
Figure 8. Dipping Tests - Oil Pickup on Aluminum
26
-------
NOTE: %
/o
WEIGHT OF OIL PICKUP _
WEIGHT OF OIL & WATER PICKUP
JLU-L
99
w 97
i i
CO
pq
Q
< 95
O
PH
O
h 1
ge 93
91
,EL (
R C 1C
o-^
X
\
o\
\
\
x
^
) 20 40 60 80 100
1 l 1
0 80 60 40 20 0
MIXTURE OF DIESEL AND BUNKER C
Figure 9. Dipping Tests - Oil Percentage Pickup on Aluminum
27
-------
In general, Aluminum was determined to be the best overall material. Other
materials often proved better in the dipping tests although usually by only the
slightest of percentages. However, from a cost standpoint, weight standpoint
(ease of handling), machinability .and reliability standpoint, aluminum was the
most advantageous material.
Any of the non-metallic materials would have to be bonded to a metal in a sand-
wich fashion for adequate strength. The reliability and survivability of such a
composite structure was in grave doubt and the cost was excessive. Of the
metallic materials, stainless steel was eliminated due to cost and poor access
of materials and mild steel was eliminated due to weight although it was a very
close competitor to aluminum and could be a direct substitute.
Figures 8 and 9 show pick-up on a dry basis, and percentage pickup (i.e., %
of oil divided by total oil and water pickup), respectively, for various Bunker 'C' /
Diesel mixtures.
STATIC TESTS IN A 10-FOOT TROUGH
A total of 246 test runs were carried out for these zero current tests. Ninety-
seven runs were made in 40-weight motor oil, 78 runs were made in diesel
oil, and 71 runs were made in Bunker 'C1 oil. The specific gravity of diesel
oil at 77°F was 0.84, of 40-weight motor oil was 0.90, and of Bunker 'C' was
0.98. Further oil data is listed in Appendix II.
The test program was divided into a number of sections.
1. Oil Type 40-Weight Motor Oil
In this series of tests with a single aluminum disk, various disk
diameters were tested at various disk immersions, in various oil
slick thicknesses from thin film up to 2.5 inches. About one-half
of the tests were made with a wiper gap of 0.025 inches in order
to leave a permanent film of oil on the disk, and the remainder of
the test runs were made with rubber wipers having light disk con-
tact. It was found that rather more oil was picked up by the rubber
wipers, other conditions being equal.
After the first few test runs, the 40-weight oil emulsified with the
water to change from a clear golden brown color to milky light gold.
28
-------
After this there seemed to be no further change with continued
testing. Because of this, the first few runs were repeated in the
emulsified oil; Figure 10 shows that at an immersion depth of 1. 5
inches with a 12 inch disk in 1 inch thickness of oil the amount of
pick-up was unchanged, but that at 4.5 inches immersion about 20%
greater pick-up was obtained with emulsified oil. All other graphs
are for emulsified oil only and are consistent with one another.
All pertinent data has been put on the graph sheets, Figures 10
to 17 inclusive, and so the firures stand on their own; however some
explanation is required. Figure 11 shows the effect of changing'from
0.025 in. wiper gap to rubber wipers for a 12 inch disk in 1.0 inch
thickness of oil for various disk immersions. Figure 12 shows the
effect of disk immersion depth for an 18-inch diameter disk with
rubber wipers. At a disk speed of 0.6 revolutions per second,
about three times as much oil was picked up at an immersion depth
of six inches as compared with an immersion depth of 2. 5 inches.
There is some evidence that the graph of pickup quantity versus
disk revolutions per second is not linear. This is probably due
to starving the disk of oil at the higher revolutions. Further dis-
cussion of starvation is presended in paragraph entitled
Figure 13 shows the effect of disk diameter on oil pickup for a
range of depths for a 1.0 inch slick thickness and 0.025 inch wiper
gap. Figures 14, 15, and 16 indicate the effect of oil slick thick-
ness for an 18-inch disk at various depths of immersion. At a
2-inch immersion depth and a slick thickness of only 3/64 inches,
the effect of starving is very ovbious as pickup decreases with
increasing disk revolutions. Figure 17 is a cross-plot showing
effect of oil slick thickness at a constant disk speed of 0.6 rps.
As would be expected, when the slick thickness reaches the immer-
sion depth, there is no further increase in oil pickup with further
increase in the slick thickness.
2. Oil Type Shell Dieseline Diesel Oil
In this series of tests with a single aluminum disk, there were
similar variations of test parameters as were made with the 40-
weight oil, with the exception that all tests were made with the
29
-------
280
PICK-UP COMPAEISON - FRESH VS. EMULSIFIED OIL
40 WT. MOTOR OIL S.G. 0.90
240
12 IN. DIA AL DISK
1. 0 IN. SLICK THICKNESS
0.025 IN. WIPER GAP
IMMERSION DEPTH
200
O 1.5 IN.
A 3.0 IN.
D4.5IN.
TAGGED POINTS - REPEAT RUNS WITH
EMULSIFIED OIL
0.4
0.5
0.6
DISK REV/SEC
0.7
0.8
0.9
Figure 10. Zero Current Oil Recovery Tests
30
-------
280
240
« 200
O
i
5 16°
O
120
80
40
COMP,
40 WT.
12 IN.
1.0 IN.
0
PRISON OF WIPER GAP WITH RUBBER WIPERS (ZERC
MOTOR OIL
DIA. AL. DIS
SLICK THICF
LEGENI
<\ B
- © "
S. G. 0.90 i
K
MESS
): 0 1.5 IN. DISK DEPTH -
C\1.5 IN. DISK DEPTH -
A 3.0 IN. DISK DEPTH -
A.3.0 IN. DISK DEPTH -
B 4.5 IN. DISK DEPTH -
0.4. 5 IN. DISK DEPTH -
HV
A
_ -<
^x
^ -
0.025 IN. GA]
RUBBER WIP
0.025 IN. GA]
RUBBER WIP
0.025 IN. GA]
RUBBER WIP
\ C
H,
) GAP)
P
ERS
P
ERS
P
ERS
1 A.
A
0
0.3 0.4 0.5 0.6 0.7
DISK REV/SEC.
Figure 11. Zero Current Oil Recovery Tests
0.8
0.9
31
-------
ZERO CURRENT OIL RECOVERY TESTS
40 WT. MOTOR OIL S.G. .90
18 IN. DIA. AL. DISK
h 1.0 IN. SLICK THICKNESS
RUBBER WIPERS
IMMERSION DEPTH
O 2.5 IN.
I
A 4.0 IN.
I
D 6.0 IN.
DISK REV/SEC
Figure 12. Zero Current Oil Recovery Tests
32
-------
280
240
PS
o
I
ft
200
160
120
80
40
40 WT. MOTOR OIL S.G. 0.90
i i i
1.0 IN. SLICK THICKNESS
0.025 IN. WIPER GAP
LEGEND:
O 8 IN. DIA. DISK, 1.0 IN. DEPTH
V 8 IN. DIA. DISK, 1.5 IN. DEPTH
Q 12 IN. DIA. DISK, 1.5 IN. DEPTH
A12 IN. DIA. DISK, 3.0 IN. DEPTH
B18 IN. DIA. DISK, 2.0 IN. DEPTH
0 18 IN. DIA. DISK, 3.0 IN. DEPTH
$18 IN. DIA. DISK, 4.5 IN. DEPTH
53 18 IN. DIA. DISK, 6.0 IN. DEPTH
0.3
0.5 0.6 0.7
DISK REV./SEC.
0.8
Figure 13. Zero Current Oil Recovery Tests - Effect of Disk Diameter and
Depth on Oil Pickup
33
-------
320
280
240
40 WT. MOTOR OIL S.G. 0.90
18 IN. DIA. AL. DISK - RUBBER WIPERS
EFFECT OF SLICK THICKNESS
DISK IMMERSION DEPTH 6 IN.
O SLICK THICKNESS 3/64 IN.
A SLICK THICKNESS 0.25 IN.
a SLICK THICKNESS 2. 50 IN.
0 SLICK THICKNESS 1. 0 IN.
(WIPER GAP 0.025 IN.)
0.3
0.5 0.6 0.7
DISK REV./SEC.
0.8
Figure 14. Zero Current Oil Recovery Tests
34
-------
280
40 WT. MOTOR OIL S. G. 0.90
I I
18 IN. DIA. AL. DISK - RUBBER WIPERS
240
EFFECT OF SLICK THICKNESS
DISK IMMERSION DEPTH 4 IN.
OSLICK THICKNESS
E
0
&3SLICK THICKNESS
1.0 IN. (WIPER GAP
0.025 IN.)
0.25 IN.
0.50 IN._
1.50 IN.
2.50 IN.
0.3
0.4
0.5 0.6
DISK REV./SEC.
0.7
0.9
Figure 15. Zero Current Oil Recovery Tests
35
-------
280
240
200
40 WT. MOTOR OIL S.G. 0. 90
18 IN. DIA. AL. DISK - RUBBER WIPERS
EFFECT OF SLICK THICKNESS
DISK IMMERSION DEPTH 2 IN.
O SLICK THICKNESS 3/64 IN.
A SLICK THICKNESS 0.25 IN.
O SLICK THICKNESS 2. 50 IN. (2. 5 IN. SLICK)
- 0 SLICK THICKNESS 1.00 IN. (WIPER
GAP 0.025 IN.)
EFFECT OF STARVING
0.4
0.5 0.6 0.7
DISK REV./SEC.
Figure 16. Zero Current Oil Recovery Tests
0.8
36
-------
280
240
200
_1
<
O
A*
!=>
160
120
80
40
40 WT. MOTOR OIL S.G. 0. 90
18 IN. DIA. AL. DISK - RUBBER WIPERS
EFFECT OF SLICK THICKNESS
DISK REVS. 0.6 R. P. S.
O DISK IMMERSION DEPTH 2.0 IN.
£ DISK IMMERSION DEPTH 4. 0 IN.
D DISK IMMERSION DEPTH 6.0 IN.
0.5
1.0 1.5 2.0
OIL SLICK THICKNESS - IN.
2.5
Figure 17. Zero Current Oil Recovery Tests
37
-------
18-inch diameter disk because oil quantity pickup was low. It
soon became evident that there was big variation in oil pickup
depending on the wiper pressure of the rubber wipers. Figure 18
shows that more than twice as much oil was picked up with heavy
wiper pressure as compared with light wiper contact. Conse-
quently, all further testing with diesel oil was made with heavy
wiper pressure. Results of single disk tests are presented in
in Figures 18 to 23 inclusive, and results for multiple disk in
Figures 24, 25, and 26. Figures 19, 20, 21, and 22 show the effects
of disk immersion depth and disk revolution speed on oil pick-up at
slick thicknesses ranging from 0.03 in. to 1.0 in., and Figure 23
is a cross-plot showing the effect of oil slick thickness at a constant
disk speed of 0.6 EPS. It is interesting that because of the low
specific gravity and low viscosity of the diesel oil there is no oil
starving until slick thicknesses of around 0.03 in. are reached. In
fact, for 0. 25 in. slick thickness and up there is no change of pick-
up at a given disk immersion depth.
Figure 24 shows what happens with 5-18 inch diameter disks side-
by-side at a spacing of 1.5 inches in a slick thickness of 0.25 inches.
Here there is evidence of severe starving in zero current conditions
when compared with 4 times the single disk values (only 8 sides wiped
with multiple disks).
Figure 25 shows that there is much less evidence of starving when the
slick thickness is increased to 1. 0 inch.
Figure 26 presents a comparison of simulated waves with smooth water
conditions for the battery of 5-18 inch diameter disks with 8 sides
wiped, in an oil slick of 0.25 inch thickness. In waves 5 inches high
with a 1. 6 second period and disk immersion depth 0.5 in., there was
about 25% greater total oil pickup than with a static disk immersion
depth of 6 inches. However, the simulated wave test may have been
unrealistic in that the confined trough tended to pump the oil .towards
the disks, and due to its light weight diesel oil does not entrain with
the water.
Once the wiper problem had been solved, the diesel tests were easy
to conduct and collection was precise, giving very little data scatter.
However, the actual quantities picked up in a given time were only
about a quarter of the pick-up with 40 weight oil. Only negligible
quantities of water were picked up with the diesel oil.
38
-------
280
240
200
O
D
O
f <
On
H
O
160
120
O
IMMERSION DEPTH
O 2 IN.
A 4 IN.
Dei
«
A
<[.
^ V
H
i
SHELL DIESELINE DIESEL OIL S.G. .82
18 IN. DIA. AL. DISK
1.0 IN. SLICK THICKNESS
RUBBER WIPERS
COMPARISON BETWEEN
HEAVY WIPER PRESSURE AND
LIGHT WIPER CONTACT
Y HEAVY \
\ f
^o
^PER PRESSl
^^^
r- LIGHT
X^-jJ
JRE
-rr
WIPER CONT
1 1
A
ACT
D-
80
40
.3
.5
.6 .7
DISK REV/SEC
.9
Figure 18. Zero Current Oil Recovery Tests
39
-------
o
I
ft
o
H
60
50
40
30
20
EFFECT
SHELL ]
OF DISK IMM]
RUBBER WIP
^==
DIE SE LINE D]
18 IN. DIA.
ERSION DEPT
ESEL OIL S.
AL. DISK
H WITH 0.003
1
ERS WITH HEAVY CONTAC
IMMERSION DEPTH
^5^==^
^-$
__ _ /» A
G. 0.82
IN. SLICK Tl
DT PRESSURE
0 2 IN.
A 4 IN.
H 6 IN.
0 0.5 IN.
i"
ilCKNESS
10
0.3
0-4 0.5 0.6 0.7
DISK REV./SEC.
Figure 19. Zero Current Oil Recovery Tests
0.8
40
-------
60
K
o
I
ft
D
i
W
U
50
40
30
s
H 20
10
0.3
SHELL DIESEL OIL 3.G. 0.82
18 IN. DIA0 AL DISK
EFFECT OF DISK IMMERSION DEPTH
-WITH 0.25 IN. SLICK THICKNESS
RUBBER WIPERS WITH HEAVY CONTACT PRESSURE
IMMERSION DEPTH O 2 IN.
A 4 IN.
D 6 IN.
0.4
0.5 0.6 0.7
DISK REV/SEC
0.8
0.9
Figure 20. Zero Current Oil Recovery Tests
41
-------
SHELL DIESEL OIL S.G. 0.82
18 IN. DIA.AL DISK
EFFECT OF DISK IMMEBSION DEPTH
WITH 0. 5 IN. SLICK THICKNESS
RUBBEE WIPERS WITH HEAVY CONTACT PRESSURE
IMMERSION DEPTH
0.6 0.7
DISK REV/SEC
Figure 21. Zero Current Oil Recovery Tests
42
-------
60
"
O
O
ft
s
H
50
40
30
20
10
SHELL DIESELINE DIESEL OIL S.G. 0.82
18 IN. DIA AL DISK
EFFECT OF DISK IMMERSION DEPTH .
WITH 1. 0 IN. SLICK THICKNESS |
. RUBBER WIPERS WITH HEAVY PRESSURE CONTACT
IMMERSION DEPTH O 2 IN
A 4 IN
D 6 IN
0.6
DISK REV/SEC
0.9
Figure 22. Zero Current Oil Recovery Tests
-------
SHELL DEESELINE DIESEL OIL S.G. 0.82
18 IN. DIA. AL. DISK - RUBBER WIPERS
WITH HEAVY WIPER PRESSURE
EFFECT OF SLICK THICKNESS AT CONST. DISK REVS. 0.6 RPS
60
50
O
I
ft
D
U
40
0 DISK IMMERSION DEPTH 0.5 IN.
O DISK IMMERSION DEPTH 2.0 IN.
A DISK IMMERSION DEPTH 4.0 IN.
H DISK IMMERSION DEPTH 6.0 IN.
(NO STARVING UNTIL VERY SHALLOW OIL DEPTHS)
30
20
10
0.5
1.0 1.5
OIL SLICK THICKNESS - IN.
2.0
Figure 23. Zero Current Oil Recovery Tests
44
-------
SHELL DIESELINE DIESEL OIL S. G. 0.82
COMPARISON BETWEEN MULTIPLE AND SINGLE DISK PICKUP
280
240
200
O
160
120
80
40
5 - 18 IN. DIA. AL. DISKS 8 SIDES WII
RUBBER WIPERS WITH FIRM CONTACT
1.5 IN. DISK SPACING
0.25 IN. OIL SLICK THICKNESS
X
«
0
0 DISK ]
A DISK ]
0 DISK :
4J
X1
X
X
x-
x*"
r
, i
^ ' -
MMERSION D
JVIMERSION E
MMERSION E
SINGLE DISI
X
/
X"
^
^
**
_ EVIDENCE
SEVERE SI
t±^>~
EPTH 2 IN.
EPTH 4 IN.
EPTH 6 IN.
: VALUES
X
/
X
^-
OF
"ARVING
==:::'^
3ED
PRESSURE
X
X
x*
-------
o
I
D
O
E-i
O
SHELL DIESELINE DIESEL OIL S. G. 0.82
COMPARISON BETWEEN MULTIPLE AND SINGLE DISK PICKUP
280
240
200
160
120
80
40
5 - 18 IN. DIA. AL. DISKS - 8 SIDES WIPED
RUBBER WIPERS WITH FIRM CONTACT PRESSURE
I I
1.0 IN. OIL SLICK THICKNESS
0 DISK IMMERSION DEPTH 2 IN.
& DISK IMMERSION DEPTH 4 IN.
H DISK IMMERSION DEPTH 6 IN.
4 X SINGLE DISK VALUES
0.3
0.5 0.6 0.7
DISK REV./SEC.
Figure 25. Zero Current Oil Recovery Tests
0.8
46
-------
SHELL DIESELINE DIESEL OIL S.G. 82
60
5-18 IN. DIA. AL. DISKS 8 SIDES WIPED
RUBBER WIPERS WITH FIRM CONTACT PRESSURE
0.25 IN. OIL SLICK THICKNESS
COMPARISON OF SIMULATED WAVES
WITH SMOOTH WATER CONDITIONS
50
DISK IMMERSION DEPTH 0 5 IN.
(WAVES 5.0 IN HIGH X 1.6 SEC. PERIOD)
K
ffi
O
I
D
X
U
h- H
PH
O
H
40
30
20
10
.3
O DISK IMMERSMN DEPTH 2 IN. (SMOOTH)
DISK IMMERSION DEPTH 4 IN. (SMOOTH)
DISK IMMERSION DEPTH 6 IN. (SMOOTH)
.4 .5 -6 .7
DISK REV/SEC
Figure 26. Zero Current Oil Recovery Tests
47
-------
3. Oil Type-Bunker 'C' Fuel Oil
This was the most difficult of all the oils to work with in that it
weathered very quickly into a heavy black tar, quickly gumming up
the apparatus. In addition there was evidence of very severe oil
starving, even with a single disk. It was obvious that about twice
as much oil was being picked up on the disk side away from the mirror
box, and so this box was removed. Measurements of quantities
collected were imprecise because flow could not suddenly be shut off.
Although large quantities of oil were picked up, water content was high
due to bubbles of water being encapsulated by the oil. Measurement
of water content was inprecise due to the black tar coating the insides
of the transparent plastic buckets. Oil slick thickness quoted is not
that near the disk, as the rotating disk produced a hole in the under-
side of the oil. However, a certain amount of test data was obtained
for the single disk, and this is plotted in Figures 27 to 34 inclusive.
Wiper gap was standardized at 0.025 in. Figures 27, 28, 29, 30, and
31 show the effect of slick thickness, far from the disk, on pick-up,
for a range of disk speeds and immersion depths. Oil starving is
evident, particularly at the higher disk pseeds in a slick thickness of
1.7 inches. Figure 32 is a cross-plot showing the effect of slick
thickness at a constant disk speed of 0.6 EPS. for the 18 inch dia-
meter aluminum disk. Here starving is evident at the lower slick
thicknesses.
Figure 33 shows the total pick-up for a 12 inch diameter disk in an
approximate slick thickness of 1.0 inch. For this test the oil had
"weathered" and the mirror box was removed for better inflow to
the disk.
The pick-up for an immersion depth of 4. 0 in. was about 20% greater
than for an earlier test on the 18 inch disk at an immersion depth of
6.0 in., see Figure 30.
Figure 34 is a plot of the water content in the pick-up as a percentage
of the total pick-up. Although there is a great deal of scatter in the
data, it is clear that disk speeds will have to be lower than 0.1
revolutions per second in order to have water content of the picked
up oil less than 10%. This is lower than the speeds that were tested.
One significant thing that was noticed about the Bunker 'C' oil is that
it "puddles" and does not spread, probably due to its high density
combined with its high viscosity
48
-------
280
EFFECT OF DISK IMMERSION DEPTH IN THIN FILM
BUNKER 'C' OIL S. G. 0.98
18 IN. DIA. AL. DISK
240
0.025 IN. WIPER GAP
g 200
-\
<;
IMMERSION DEPTH.
160
o
£
O
EH
120
80
02 IN.
A4 IN.
06 IN.
40
0.7
0.8
DISK REV./ SEC.
Figure 27. Zero Current Oil Recovery Tests
49
-------
280
ZERO CURRENT
OIL RECOVERY TESTS
240
200
IMMERSION DEPTH
1 1
BUNKER "C" OIL S.G. .98
18 IN DIA. AL. DISK
0.25 IN. SLICK THICKNESS
0.025 IN WIPER GAP
K
W
o
EH
O
EH
160
O
A
D
2 IN.
4 IN.
6 IN.
120
80
40
.2
.4 .5 .6
DISK REV/SEC
.8
Figure 28. Zero Current Oil Recovery Tests
50
-------
280
240
BUNKER 'C» OIL S. G. 0.98
18 IN. DIA. AL. DISK
.EFFECT OF DISK IMMERSION DEPTH
WITH 0.5 IN. SLICK THICKNESS
200
0.025 IN. WIPER GAP
IMMERSION DEPTH O 2 IN.
- A 4 IN..
D 6 IN.
K
ffi
5 160
a
ft
EH
O
120
80
40
J.3
0.4
0.5 0.6 0.7
DISK REV./SEC.
0.8
Figure 29. Zero Current Oil Recovery Tests
51
-------
280 -
240
200
ffi
o
I
160
OH
BUNKER'C' OIL S. G. 0.98
18 IN. DIA. AL. DISK
EFFKCT OF DISK IMMERSION DEPTH
WITH 1.0 IN. SLICK THICKNESS
0.025 IN. WIPER GAP
IMMERSION DEPTH
© 2 IN.
4 IN.
H 6 IN.
120
0.5 0.6
DISK REV./SEC.
Figure 30. Zero Current Oil Recovery Tests
52
-------
280
240
200
o
I
p^
ID
I
o
160
H 120
O
SO
BUNKER 'C' OIL S.G. .98
18 IN. DIAM. AL. DISK
EFFECT OF DISK IMMERSION DEPTH
WITE 1.7 IN. SLICK THICKNESS
0.025 IN. WIPER GAP
.4 .5 .6 .7 .8
DISK REV./SEC.
Figure 31. Zero Current Oil Recovery Tests
53
-------
o
I
ft
U
ft
H
O
H
BUNKER
18"in. DIA. AL.
280
C' OIL S.G. 98
DISK .025 IN.
240
EFFECT OF SLICK THICKNESS AT
CONST. DISK REVS. 0.6 EPS
DISK DEPTE 2 IN.
DISK DEPTE 4 IN.
DISK DEPTE 6 IN.
200
160
120
80
40
EFFECT OF
STARVING
OIL SLICK THICKNESS - IN.
Figure 32. Zero Current Oil Kecovery Tests
54
-------
280
240
BUNKER 'C1 OIL S.G. .98
12 IN. DIA. AL. DISK
EFFECT OF DISK IMMERSION DEPTH
WITE 1.0 IN. SLICK THICKNESS (APPROX.)
0.025 IN. WIPER GAP
200
O
O
H
O
H
160
120
40
NOTE: OIL WEATHERED
MIRROR BOX REMOVED
X
A
A.
IMMERSION DEPTF
O 1.5 IN.
3.0 IN.
4.0 IN.
.3
.4
.5
DISK REV./SEC
.7
Figure 33. Zero Current Oil Recovery Tests
55
-------
I
PH
O
O
P;
w
BUNKER «C» OIL S.G. 0.98
18 IN. DIA. ALUM. DISK
WATER CONTENT IN TOTAL PICKUP
WITH 0.25 IN. SLICK THICKNESS
0.025 IN. WIPER GAP
0.3
0.5 0.6 0.7
DISK REV./SEC.
Figure 34. Zero Current Oil Eecovery Tests
56
-------
TESTS IN A 300 FOOT TOWING BASIN
A total of 216 test runs were carried out for this series of tests. 177 of
these runs were made with SAE 40 weight motor oil in smooth water. 9 runs
were made in waves combined with current with 40 weight oil. 30 runs were
made with Bunker 'C' oil in smooth water.
The main purpose of the tests was to find the effect of current and disk spacing
on the oil pick-up rate of a multi-disk system, and to find the best direction of
disk rotation relative to the current. The data collected is plotted in Figures 35
to 53 inclusive.
Figures 35 and 36 show the results for tests run with the disks rotating both with
and against the current to determine the best operating condition for all subse-
quent tests. The test conditions were oil thickness 0.25 in., disk spacing
1. 5 inches, and disk immersion depth for the 5-18 inch diameter disks 6.0 inches.
It was established conclusively that the disk should rotate with the current for
minimum relative velocity, rather than against the current for maximum rela-
tive velocity. All subsequent testing was conducted with the disks rotating with
the current.
The first few tests runs were performed with the five disks spaced at 1-1/2
inches between disks and with six inch immersion into the liquid. All five disks
were wiped on a total of ten sides, and the quantities collected. After this all
following tests were conducted with the center disk providing the test sample
and the other four disks being wiped and the liquid then discharged downstream
of the disk/liquid interface.
Figure 37 is a plot of Total Pick-up versus disk revolutions for a series of
current speeds for an oil slick thickness of 0.25 inch. Disk spacing was 1.5
inches and disk immersion depth 6.0 inches. Also laid on this graph is the
appropriate zero current line from tests in the ten foot trough. The maximum
current speed was 3.0 knots and this was combined with excessive disk revolu-
tions up to 2.2 revs./sec. resulting in a much reduced pick-up. At disk rates
of 2 c.p.s., water was thrown everywhere, including over the test personnel;
subsequent tests were performed at disk rates of 1.5 c.p.s. maximum. A
cross-plot of this graph at constant disk revs, of 0.8/sec. (Figure 48) shows
maximum pick-up at a current speed of 2 knots, followed by a very rapid fall
off. Large quantities of water were collected under all test conditions.
57
-------
Figures 38, 39, and 40 cover conditions where disk spacing was increased to
3. 0 inches and oil thickness to 1. 0 inches. Selected runs were made at
three immersion depths; six, four, and two inches. Also laid on these three
figures are the zero current lines from tests in the 10 foot trough. Cross-
plots of these graphs at constant disk revs, of 0.8 per sec. are given in
Figure 47. At an immersion depth of 6.0 inches, maximum pick-up is at
2 knots, followed by a very rapid fall off with increasing current, as before.
At 2 inches immersion depth current speed seems to have little effect on
pick-up between zero and three knots. Again, large quantities of water were
noted in test samples at four and six inch immersion. An attempt was made
to conduct test runs at high current speeds in excess of 3 knots, without
success. The test time was too short and in addition the water would spill
into the mirror box.
Figures 41, 42, 43, and 44 cover conditions with disk spacing 1.5 inches and
oil thickness 1.0 inches. For the data on Figure 42 the test fixture was modi-
fied to add a deflector blade on either side of the center (test) disk. This
deflector was a wedge 1/2 inch thick, with a three inch chord and a seven inch
span. The deflectors were installed in such a fashion that the trailing edge of
the wedge was flush with the trailing (or downstream) edge of the disks. The
wedges were placed so as to completely penetrate the oil layer at all immer-
sion depths.
Five test runs were made during which it was noted that there appeared to be
excessive drainage into the test disk from the oil wiped off the adjacent disks.
A barrier was added to channel the oil away from the center disk and the test
series was continued. After fourteen runs the two deflectors were removed
from the test fixture and test runs were repeated at four inch immersion to
assess the effectiveness of the deflectors. The test data was erratic and
inconclusive.
It is noted that the three inch disk spacing was more effective than the 1-1/2
inch spacing for a given set of operating conditions, See Figure 49.
Oil condition SAE 40 weight two inch thick, was disks spaced three inches apart
at an immersion depth of 6. 0 inches, yielded the results of Figure 45. Selected
runs were made at all three immersion depths in an attempt to obtain a correla-
tion with the previous run series. It was noted that at this oil thickness the
recovery was rather incomplete in that there was very little clean up except at
high immersion depths, current speeds and disk rates. In most runs the water
content of the samples was quite low.
58
-------
Data for oil condition SAE 40 weight, three inch thick, disks spaced at 1-1/8
inches apart and set to a depth of 6.0 inches is plotted in Figure 46. Water
content of the samples was very high.
Oil condition SAE 40 weight one inch thick, disks spaced at 1-1/2 inches apart.
This test series was a repeat of the previous series with the addition of wave
action to the test environment. Runs were made at four inch and two inch
immersion depths, see Figures 50 and 51 respectively. The ability of the
system to recover oil was definitely reduced at the two inch depth, but was
increased at the four inch depth. The wave height was approximately two
inches and the period something less than one second.
OIL CONDITION BUNKER 'C', APPROXIMATELY 0.8 INCHES THICK AND
DISK SPACING 1.5 INCH.
At the six inch immersion depth there was an excessive amount of oil collected,
and spilling occurred out of the collection trough. At four inch immersion
(see Figure 52) the test could handle the oil but test data was very erratic and
inconclusive. It was determined that the Bunker 'C' oil is so viscous that in
some instances, the collection pan, which is a reference volume, does not
fill completely at time of overflow. The collection rate is therefore in error.
This error is amplified at high discharge rates. The solution to the problem
was to tilt the collection pan to aid the oil flow to ensure complete filling during
sampling time. This was done on runs 208 through 216 for a two inch immer-
sion depth (see Figure 53). The data obtained on these runs is quite reliable.
The data on Figures 52 and 53 shows evidence of a high degree of oil starving
at the higher disk revolutions. The Figures indicate that disk revolutions should
be lower than 0.4 revs./sec, with 18 inch diameter disks in order to avoid
starvation.
59
-------
40 WT. MOTOR OIL S.G. 0.89
18 IN. DIA. ALUM. DISKS
5 DISKS, ALL WIPED AND COLLECTED
EFFECT OF CURRENT DIRECTION ON PICKUP
AT CONST. DISK REVS. 1.0 RPS
200
175
150
125
H
O
K
ffi
O
100
75
50
25
OIL THICKNESS 0.25 IN.
DISK SPACING 1.50 IN.
DISK IMMERSION DEPTH 6.0 IN.
RUNS 7-12 1.0 RPS
1/4 1/2
3/4 1 1-1/4 1-1/2 1-3/4
CURRENT - "-KNOTS
" 2-1/4
Figure 35. Oil Recovery Tests Smooth Water - Current Conditions
60
-------
200
175
150
125
Q° TOTAL
GAL/HR 100
75
50
25
4
1
0 WT. MOr
8 IN. DIA.
FOR OIL £
ALUM. D]
.G. 0.89
[SKS
5 DISKS, ALL WIPED AND COLLECTED
EFFECT OF CURRENT DIRECTION ON PIC
AT CONST. DISK REVS. 0.6 RPS
0
D
D
q
""^^
EL THICK!
ESK SPACI
ISK IMME]
[
) ^^^^f^"
I
r
TESS
NG
RSION DEF
)
^^
J
s
0.25 ]
1.50 ]
TH 6.0 n
/~n
Vltf*^
<
N.
JN.
\.
?&*L
vp^
' AGAINST
RUNE
0.6
KUP
CURREN'
1-6
RPS
'
1/4 1/2 3/4 1 1-1/4 1-1/2 1-3/4 2 2-1/4
CURRENT KNOTS
Figure 36 . Oil Recovery Tests Smooth Water - Current Conditions
61
-------
EFFECT OF CURRENT. DISK IMMERSION 6.0 IN
40 WT. MOTOR OIL S. G. 0.89
18 IN. DIA. ALUM. DISKS
5 DISKS, 10 SIDES WIPED, 2 SIDES COLLECTED
OIL THICKNESS 0.25 IN.
DISK SPACING 1.50 IN.
DISK IMMERSION DEPTH 6.0 IN.
O CURRENT 0.25 KT
A CURRENT 0.5 KT
O CURRENT 1.0 KT
0 CURRENT 2.0 KT
* CURRENT 3.0 KT
ZERO CURRENT
TESTS IN 10 FT.
TROUGH
0-6 1.0 1.4
DISK REV ./SEC.
Figure 37. Oil Recovery Tests - Current Conditions
62
-------
40 WT. MOTOR OIL S.G. 0.89
5-18 IN. DIA. ALUM. DISKS
OIL THICKNESS 1. 00 IN.
DISK SPACING 3. 00 IN.
DISK IMMERSION DEPTH G.O IN.
700
600
500
K
,-1
<
O
i
400
300
O
200
100
CURRENT 3.0 KT.
CURRENT 0.25 KT.
CURRENT 0.5 KT.
CURRENT 1.0 KT.
CURRENT 2.0 KT.
ZERO CURRENT TESTS
IN 10 FT. TROUGH
0.8 1.2 1.6
DISK REV./SEC.
Figure 38. Oil Recovery Tests - Current Conditions
2.0
63
-------
40 WT. MOTOR OIL S.G. 0. 89
5-18 IN. DIA. ALUM. DISKS
OIL THICKNESS 1. 00 IN.
DISK SPACING 3. 00 IN.
DISK IMMERSION DEPTH 4. 0 IN.
600
500
400
a
o
&
o
8
300
200
100
CURRENT 0.25 KT.
CURRENT 0.5 KT.
CURRENT 1. 0 KT.
CURRENT 2.0 KT.
CURRENT 3.0
ZERO CURRENT TESTS
IN 10 FT. TROUGH
1.2 1.6
DISK REV./SEC.
Figure 39. Oil Recovery Tests - Current Conditions
2.0
64
-------
40 WT. MOTOR OIL S.G. 0.89
5-18 IN. DIA. ALUM. DBKS
OIL THICKNESS 1. 00 IN.
DISK SPACING 3. 00 IN.
DISK IMMERSION DEPTH 2. 0 IN.
600
500
Q
T-l
tf
O
400
300
ft
200
100
KEY:
0 CURRENT 0.25 KT.
A CURRENT 0.5 KT.
D CURRENT 1.0 KT.
0 CURRENT 2.0 KT.
* CURRENT 3.0 KT.
ZERO CURRENT TESTS
IN in VT1 T'-RnTTr'TT
*-
'^""
0 OD
««»
A
0D
o
*
0.4
1.6
0.8 1.2
DISK REV./SEC.
Figure 40. Oil Recovery Tests - Current Conditions
2.0
65
-------
700
EFFECT OF CURRENT, DISK IMMERSION 6.0 IN., CHANGED
DISK SPACING. 40 WT. MOTOR OIL S.G. 0.89
5-18 IN. DIA. ALUM. DISKS
600
500
OT
ii
P
d.
O
i
i
O
o
H
400
300
200
OIL THICKNESS - 1.00 IN.
DISK SPACING - 1.50 IN.
DISK IMMERSION DEPTH - 6»0 IN.
KEY:
A CURRENT 0.5 KT.
O CURRENT 0.75 KT.
D CURRENT 1.0 KT.
* CURRENT 1.5 KT.
0 CURRENT 2.0 KT.
ZERO CURRENT
TESTS IN 10 FT.
TROUGH (FIG. 13)
0
SINGLE POINT FOR 0.5 KTS.
100
CURVE FOR ZERO CURRENT
TESTS IN 10 FT. TROUGH
(FROM FIG. 13)
0.4
0.8 1.2 1.6
DISK REV/SEC
2.0
Figure 41. Oil Recovery Tests - Current Conditions
66
-------
700
600
EFFECT OF CURRENT COMBINED WITH FLOW DEFLECTORS
40 WT. MOTOR OIL S.G. 0.89
5-18 IN. DIA. ALUM. DISKS
OIL THICKNESS 1.00 IN.
DISK SPACING 1.50 IN. ~^T
DISK IMMERSION DEPTH 6.0 IN.
FLOW DEFLECTORS
500
K
o
I
ft
D
W
O
o
H
400
300
200
100
SINGLE POINT
FOR 0.5 KT3.
"ZERO CURRENT TESTS
IN 10 FT. TROUGH (FIG. 13)
KEY:
A CURRENT 0.5 KT.
O CURRENT 0.75 KT.
D CURRENT 1.0 KT.
K CURRENT 1.5 KT
0 CURRENT 2.0 KT.
«£> CURRENT 3.0 KT.
0.4
0.8 1.2 1.6
DISK REV/SEC
2.0
Figure 42. Oil Recovery Tests - Current Conditions
67
-------
600
500
w
II
° 400
K
O
i 300
O
1 (
PM
H
O
H
200
100
EFFECT OF CURRENT, DISK IMMERSION 4.0 IN.
40 WT. MOTOR OIL S.G. 0.89
5-18 IN. DIA. ALUM. DISKS
OIL THICKNESS 1.00 IN.
DISK SPACING 1.50 IN.
DISK IMMERSION DEPTH 4.0 IN.
KEY:
A CURRENT 0.5 KT.
0 CURRENT 1.0 KT.
0 CURRENT 2.0 KT.
a
o
0.4
1.6
0.8 1.2
DISK REV/SEC
Figure 43. Oil Recovery Tests - Current Conditions
2.0
68
-------
600
500
S3 400
Q
O
0
H
O
300
200
100
EFFE<
5-18 I
40 WT
OIL T
DISK j
DISK ]
KE1
CT OF CURRE
N. DIA. ALUI
. MOTOR Oil
HICKNESS l.C
SPACING 1.50
[MMERSION D
T .
;NT, DISK IM:
ft. DISKS
, S.G. 0.89
)0 IN.
IN.
EPTH 2.0 IN.
0 CUREENT 1.0 KT.
0 GUI
*CUI
IRENT 2.0 KT
IRENT 3.0 Kl
>*
X
i
i
Jlr
VIERSION 2.0
J>^
/
0
IN.
/
*
0.4
1.6
0.8 1.2
DISK REV/SEC
Figure 44. Oil Recovery Tests - Current Conditions
2.0
69
-------
40 WT. MOTOR OIL S.G. 89
A CURRENT 0.5 KT.
D CURRENT 1.0 KT.
0 CURRENT 2.0 KT.
EFFECT OF CURRENT
- CHANGED DISK SPACING
5-18 EN. DIA. ALUM. DISKS
OIL TEICKNES3 2.0 IN.
DISK SPACING 3.0 IN.
DISK IMMERSION DEPTH 6.0 IN.
0.8 1.2
DISK REV/SEC
2.0
Figure 45. Oil Recovery Tests - Current Conditions
70
-------
I I I I
EFFECT OF CURRENT - CHANGED DISK SPACING
40 WT. MOTOR OIL S.G. 0.89
5-18 IN. DIA. ALUM. DISKS
OIL THICKNESS 3.00 IN.
DISK SPACING 1.13 IN."
DISK IMMERSION DEPTH 6.0 IN.
A CURRENT 0.5 KT
D CURRENT 1.0 KT
0 CURRENT 2.0 KT
0.8 1.2 1.6
DISK REV/SEC
Figure 46. Oil Recovery Tests - Current Conditions
71
-------
600
500
400
o
300
1-1
g
o
200
100
40 WT. MOTOR OIL S.G. 0. 89
5-18 IN. DIA. ALUM.DEKS
CONSTANT DISK REVS. 0. 8/SEC.
OIL THICKNESS 1. 00 IN.
DISK SPACING 3. 00 IN.
DISK IMMERSION
DEPTH 6.0 IN.
1.0 2.0 3.0
CURRENT - KNOTS
Figure 47. Oil Recovery Tests - Current Conditions
72
-------
GO
3
o
v;
O
O
H
320
EFFECT OF CURRENT - CONST. DISK REVS. 0.8 R.P.3.
18 IN. DIA. ALUM DISKS
OIL THICKNESS 0.25
DISK SPACING 1.50 IN.
DISK IMMERSION DEPTH 6.0 IN
DISK REVS. 0.8/SEC
40 WT. MOTOR OIL S.G. 0.89
160
120
80
40
1.0
2.0
3.0 CURRENT - KNOTS.
Figure 48. Oil Recovery Tests - Current Conditions
73
-------
700
600
500
1 <
Q
ti
3
\. 400
O
i
0 300
1 I
PH
i-l
0
H
200
100
0
1.
40 WT.
MOTOR OIL S.G
. 0.89
5-18 EN. DIA. ALUM. DISKS
EFFECT OF DISK SPACING ON PICK-UP
OIL THICKNESS 1.00 IN.
DISK IMMERSION DEPTH 6.0 IN.
DISK RI
x*
**"
^--
.,
:vs. 0.8 REVS/S]
«
^
^^^
^
EC
.,
s^
^
^
^^^"^
_______
\
^'
\>
*
^
0.5^
. "
e^
^^
T.
0 1.5 2.0 2.5 3.0
DISK SPACING - IN.
Figure 49. Oil Recovery Tests - Current Conditions
74
-------
600
500
400
PH
O
i 300
40 WT. MOTOR OIL S.G. 0.89
5-18 IN. DIA. ALUM. DISKS
OIL THICKNESS 1. 00 IN.
DISK SPACING 1. 50 IN. /
STATIC DISK IMMERSION DEPTH 4. 0 IN. /
REGULAR WAVES 2+ IN. x 1. 0 SEC. PERIOD /
%
y
0
/ /
/
/°
'
D
n CUR
y^\ SMOOTH WATER
1
SNOT
0 CUP
r
,
/
/
^^ SMOOT
2 KNOT
RENT 1. 0 KT
RENT 2.0 KT
H WATER
'S
200
100
0.4
0.8 1.2
DISK REV./SEC.
1.6
2.0
Figure 50. Oil Recovery Tests - Wave & Current Conditions
75
-------
600
40 WT MOTOR OIL S.G. .89
5 18 IN. DIA ALUM. DISKS
OIL THICKNESS 1.00 IN.
DISK SPACING 1.50 IN.
STATIC DISK IMMERSION DEPTH 2.0 IN.
REGULAR WAVES 2 + IN. X 1.0 SEC. PERIOD
D CURRENT 1.0 KT
SMOOTH WATER
1 KNOT
0.8 1.2 1.6
DISK REV/SEC
Figure 51. Oil Recovery Tests - Wave & Current Conditions
2.0
76
-------
900
0.4
1.5 K
BUNKER C OIL S.G. 0.98
EFFECT OF CUaRENT, DI3K IMMERSION 4.0 IN.
5-18 EN. DIA. ALUM. DISKS
OIL THICKNESS APPROX. 0.8 EN.
DISK SPACING 1.50 IN.
DISK IMMERSION DEPTH 4.0 IN.
KEY:
A CURRENT 0.5 KT.
O CURRENT 1.0 KT.
K CURRENT 1.5 KT.
NOTE:
EVIDENCE OF STARVING AT
HIGHER DISK REVS.
5 KT.
8 1.2 1.6
DISK RFV/SEC
2.0
2.4
Figure 52. Oil Recovery Tests - Current Conditions
77
-------
700
600
500
M 400
O
i
ft
O
I I
ft
H
O
H
300
200
100
1 1
BUNKER C OIL S.G. 0.98
EFFECT OF CURRENT, DISK IMMERSION 2.0 IN.
OIL THIC
DISK SP^
DIbK IMA
5-18 IN.
]KNESS APPR
^CDSfG 1.50 IN
VERSION DEP
DIA. ALUM.
B
a
A
««
0
A
OX. 0.8 IN.
.
in A . 0 IJN .
DISKS
a
A NO
EV
AT
KEY;
A CURR1
Hr'TTTJTJT
L/ U -tutt-l
K CURRI
Id
K
TE:
IDENCE OF J
HIGHER DIS
5NT 0.5 KT.
""ATT 1 r> VT
jlN 1 ± . U IV 1
:NT 1.5 KT.
STARVING
K REVS.
0.4
0.8
1.2
1.6
2.0
DISK REV/SEC
Figure 53. Oil Recovery Tests - Current Conditions
78
-------
SECTION VIII
TECHNICAL DISCUSSION
STARVATION
Starvation of the disk is defined as a reduction of oil pick-up rate due to
reduction of oil quantity adjacent to the disk. The fall off in oil quantity,
which may become total, is due to insufficient oil feed to the disk to satisfy
the oil pick-up rate. Factors affecting this are current, disk spacing, disk
rotation rate, and oil properties, such as specific gravity, viscosity and
surface tension.
The oil properties determine the oil spreading rate, which in turn affects the
oil flow rate into the disk sides. Oil properties also affect the disk pick-up
rate, and thus the demand for oil. Bunker 'C' oil, which has high viscosity
and high specific gravity, has a very low spreading rate, but has a very high
pick-up rate when the supply is maintained. Consequently it is very susceptible
to starvation. Diesel oil, on the other hand, with its low viscosity and low
specific gravity, has a very high spreading rate but low pick-up rate; it is much
less liable to create a starvation condition.
In zero current conditions starvation manifests itself visually as a deep hollow
in the undersurface of the oil surrounding the disk, so that in effect the disk is
operating in an oil thickness which is much less than that of the oil 1/2 disk
diameter away from the disk. This effect is compounded by adjacent disks
which interfere with one another and prevent the oil flow from turning into the
disk sides. It is expected that starvation can be minimized by proper design
as follows:
1. Sufficient oil inflow to the disks either by material current flow, or
by driving the disks system towards the oil.
2. Correct disk spacing.
3. Directing the oil into the disk sides by means of deflectors. This
should be further investigated.
4. Correct disk rpm.
79
-------
HERDING
For picking up Bunker 'C' or crude oil, both of which have a low spreading rate
and tend to drift into an elongated slick under the influence of the prevailing
winds and current, it is suggested that herding booms be attached to the bow of
the barge in a V-shape.
Diesel oil, which has a very high spreading rate, rapidly becomes a thin slick
with a thickness of only 1 or 2 millimeters. To pick up 50, 000 gallons per
hour with negligible water content it is necessary to contain the oil and build it
up to a thickness of at least one-half inch. Fortunately diesel oil has low
specific gravity and does not entrain with the water easily, so it should be pos-
sible to contain it with an anchored barrier system up to a current spread of
1 knot. The recovery barge would then have to operate within the barrier
system.
Alternatively the powered disk recovery system could be part of the anchored
barrier system, by putting the disks at the apex of the V-formation herding
barriers.
SUPPORT PLATFORM AND STORAGE UNIT
A possible support platform and storage unit consisting of standard offshore
barge was examined.
A pick-up rate of 50, 000 gallons per hour equals 1190 barrels per hour. A
tank barge 250 ft x 44 ft-6 in. has a capacity of 25, 000 barrels of fuel oil. It
could therefore operate with a powered disk system for 21 hours working as an
independent unit.
A tank barge 320 ft x 55 ft-4 in. holds 56, 000 barrels of fuel oil. It could
operate with a powered disk system for 47 hours working as an independent unit.
The above volumes of oil are of course reduced by water pick-up.
In order to maintain a relatively constant disk depth of immersion it would be
desirable for the barge to have a natural frequency about 1/10 times the wave
frequency. A 5 ft wave height is high Sea State 3 with a wave period of about
4. 7 sees and a wave length of 100 ft. (The wave height is defined as the height
of the highest 1/3 of the waves.) The wave frequency is 1/4. 7 = 0.213 cycles/
sec. Therefore the barge natural frequency should be 0.213 cycles/sec or
a natural period of 47 sees. This is too drastic a requirement.
80
-------
The relationship between ship speed, ship length, wave length, and natural
period of oscillation is illustrated in Figure 54 of "Principles of Naval Archi-
tecture" by J. P- Comstock, (Ref. 2). Calculations are made using this graph,
Let us first assume a 100 ft length barge with a speed of 5 knots. VA/L =
5/10 = 0. 5. Wave length divided by ship length = 1.0. If the wave length is
equal to, or greater than the ship length, then we are in the zone of severe
motions. This is the case here.
The period-length ratio T/N/L is 0.325
T = 0.325 x 10
= 3.25 sees.
The wave period is 4.7 sees.
Now assume a 250 ft length barge operating at a speed of 3 knots.
V/\TL = 3/15. 8 = 0.19
Wave length divided by ship length = 0.4.
From Ref. 2, the period-length ratio is 0.24.
T = 0.24 x 15.8 = 3.8 sees.
So it is obviously not possible to move away from the wave frequency by a
factor of more than about 25 percent; however, Ref. 2 indicates that this is
well into the zone of moderate motions and dry decks in irregular storm seas.
A tank barge of 250 ft in length would be satisfactory both from the ship
motions viewpoint, and for storage capacity.
EFFECT OF WIND
The effect of wind may be obtained from Reference 1, Page 3-11, which
assumes a wind-induced surface current proportional to the wind velocity.
The actual surface current will be between 2 and 3 percent of the winds veloc-
ity from basic oceanographic data. The results of Ref. 1 tests showed this
constant to be slightly over 1 percent. It can conservatively be assumed that
81
-------
oil pick-up can be predicted in wind and current by adding 2. 5 percent of the
wind velocity to the current velocity. The difference between model results
(1 percent) and the 2-3 percent observed in the ocean can be explained by the
very short fetch in the test set up. From this, a 20 mph wind is equivalent to
a 0.434 knot current. This would be added to the 2 knot design current to give
2.43 knots.
82
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SECTION IX
THEORETICAL MODEL AND COMPARISON
WITH EXPERIMENTAL RESULTS
THEORETICAL MODEL OF THE DISK SYSTEM
On the basis of the experimental data from tests conducted over wide ranges of
the pertinent parameters involving oil properties, geometric and dynamic
characteristics of the test apparatus, a theoretical model may be constructed
which, when validated by comparison with the experiments, would allow one to
design a full-scale system to operate under realistic oil slick conditions with
predictable performance. In the following paragraphs such a theoretical model
is developed, resulting in a set of generalized performance curves relating the
pertinent parameters in terms of three dimensionless quantities which account
for oil type, oil slick thickness, disk geometry, disk rotation rate and oil pump-
ing rate. This model is then compared with the experimental results in the
chapter following; and, finally, is used to develop a set of design criteria for a
full-scale system.
Upon observing the oil pick-up mechanism of the rotating disk it can be readily
concluded that the basic process is one of boundary-layer formation on a sur-
face moving through a finite body of two viscous fluids. Because of the differ-
ences in properties of the two fluids - water and oil - it is possible, under
appropriately controlled conditions, for the moving surface to form only an oil
boundary layer. The object of establishing a theoretical model is to describe
analytically the oil boundary-layer formation process in terms of the properties
of the oil and the geometric and mechanical constraints of the oil recovery
system. The general configuration to be analyzed is shown in Figure 54 below.
A disk of radius "R" is immersed to a depth of "D" in an oil slick of thickness
"d." The chord at the immersion line is "C." The disk rotates at a rate "u>."
The oil pick-up mechanism may be depicted as shown in Figure 55.
In this vertical section of the disk is shown the oil boundary-layer of thickness
"6," being pulled from the oil pool of thickness "d" up the disk at a vertical
velocity of GJX, where x is the horizontal distance from the center of the disk
to the point in question, as seen in Figure 55. The tangential velocity of the
disk element at this point is wr, and its vertical component is tor cos 6 = wx.
83
-------
o
Figure 54. Disk Oil Recovery Configuration
-..." ';-*. "OIL ': / . d ;.;.-.
, . .._. . .
DISK
Figure 55. Oil Boundary-Layer Formation on Disk
84
-------
Consider now the boundary-layer on the disk at the point where it just emerges
from the slick, shown in the inset in Figure 55, where the velocity profile of
this boundary-layer is depicted. The equation of motion of this layer may be
developed by considering the equilibrium of forces acting on a differential
element of thickness dy and height dz in the layer, as seen in Figure 56.
1
gdm
dz
Figure 56. Equilibrium of Forces Acting on Boundary-Layer
The shearing forces F-^ and F£ act on opposing faces of this volume element,
and there is a body force gdm due to gravity. The equilibrium is expressed as
- gdm = 0
(1)
where the shearing force
, ,
F = - u - dx dz
dy
and
dm = p dx dy dz
where dx is the depth in the x-direction.
The differential equation resulting from (1) is
__
dy v dy/
dy\ _ Pg
(2)
85
-------
Integration of Equation (2) yields
v = £i. y + Ay + B (3)
At the disk surface y = 0, and v = cox, therefore the integration constant B in
Equation (3) is
B = ojx
At the edge of the boundary layer y = , so that
v = £! 62 + A6 + wx (4)
from which the constant of integration, A, can be expressed, in terms of
and 6, as
A =
Equation (3) now becomes
v = y2+!
It remains to determine 6 and V5 (the boundary -layer thickness and the velocity
at the edge of the boundary-layer) , which can be done by considering boundary
conditions at the juncture of the horizontal oil slick surface and the vertical
surface of the edge of the boundary-layer.
Figure 57 depicts the condition at this juncture where the shearing force at the
edge of the boundary-layer is balanced by the surface tension of the slick
surface.
86
-------
DISK
h,
o
' ' Ydx / OIL 7T7tV '
Figure 57. Boundary Conditions
F -Ydx = 0
M-
(7)
The shearing force F^ is calculated from the velocity gradient at the edge of
the boundary-layer, using Equation (6),
r - cox) h dx
6 / J 6
(8)
Combining Equations (8) and (7) and rearranging, a quadratic equation in 6
results:
2 2Y .
6 +: 6
pgh& pg
v, - cox = 0
(9)
from which a solution for 6 in terms of h is obtained.
6 =
V - OJX
6 /
(10)
The oil surface "fillet" height 115 can be estimated from a balance of the sur-
face tension and the gravity force, as shown in Figure 58.
87
-------
T
Ydx
dh
dh
Figure 58. Oil Fillet
- pgh dx dy = 0
The differential equation resulting from this force balance is
Pgh = _d_
V dy
dh
dy
_d
dh
(11)
Integrating once yields
Pgh
2Y
+ C
(12)
Far from the disk, in the slick,
h = 0
-------
and
f = 0
dy
so that
C = 1
At the edge of the fillet next to the disk
h = h.
and
dh
dy
= oo
Therefore,
2V
-i
or
h /^
"c = A /
6 \/Pg
(13)
Substitution of (13) into (10) yields
6 =
V
pg
- v
\
-
/
89
-------
This may be put into dimensionless form:
(14)
where
(15)
Returning now to the determination of vs, it is seen that the continuity of flow
from the slick up to the disk suggests that V5, on the average across the chord,
is equal to the average lateral flow of the slick towards the disk. If Q is the
volume of oil picked up by both sides of the disk per unit time, and if the length
along the "water line" where oil is picked up is L, the preceding statement about
continuity is
Q_ =
Ld V6
Noting in Equation (14) that the boundary-layer thickness is zero at a finite
distance x = x§ from the disk center-line, then
wx = v = Q_
and
L = 2 (£ - s
so that
Q
90
-------
and
v =
2Q
Cd
(18)
1 + . 1 -
8Q
Equations (18) and (14) may be substituted into Equation (6) to yield an equation
for the velocity profile in the oil boundar-layer in terms of the total oil pick-up
rate.
The pick-up rate per unit width along the chord is
n
- = I vdy =
2 y
J + I v
6 \ 6
dy
(19)
The total rate of pumping for both sides of the disk along the chord from Xc to
C/2 is then
fC/2/dQ\ rC/2
Q = 2 1 (to) ^ = J 6
6 ] dx
(20)
This equation is made dimensionless by multiplying by
2pg / u \
- \4 Y/ :
With a change of variables
(22)
91
-------
Equation (20) becomes
in which
3max Y
and
-2
(23)
(24)
by Equation (14).
Integration of Equation (23) yields
iQ
From (24)
4jx
Y
Y \ Y
4
3
1
-
5
r
- coC -
Y
max
3/2
(25)
max
i i
J
(27)
92
-------
and from (18) and (27) it can be shown that
/4u.\ /
'( ) = ooC I 5 d (28)
\ Y / \ 2 |j. / max v '
3max \ ,.
d
Substitution of (27) and (28) into (26) results in an expression for wC in terms
of
3/2
5 £ +4 + (| - 4) (£ +1)
^- "K»^ 3 ma} ,- m\x ^^^ <-
I^V^^1)-'^
Equation (28) can be re-written as
IPS Q^ = ^~~ | A yr& d j ( x _ ^ ) (30)
O
Equations (29) and (30) are thus two parametric equations in £max for the disk
rotation rate and the disk oil pumping rate. By choosing suitable values of
^max' for any Siven values of the oil properties and disk geometry, the dimen-
sionless pumping rate Q E M/Y \/Pg/Y Q/C can be plotted against the dimen-
sionless rotation rate co E M/YwC, as has been done in Figure 59. Three
curves are shown, for values of the dimensionless slick thickness d E "/pg/Y d
from 0.1 to TO (very thick slick).
In order to gain better physical feeling for this universal pumping rate equa-
tion, it would be useful to tabulate the actual values of the physical constant
associated with the three types of oils studied in the experimental program, as
well as some examples of typical numbers resulting from representative values
of the physical and geometric parameters.
93
-------
-4
Figure 59. Theoretical Model Results
94
-------
Diesel 40 weight Bunker C
Surface Tension Y 28.5 30.0 34.6 dynes cm'1
-2 -1 i
Viscosity p. 4.2x10 5.0 50.6 gm cm sec"
Density p 0.842 0.895 0.979 gm cm"3
H/Y 1.48xlO~3 l.GYxlo"1 1.47 cm'1 sec
^f 5.38 5.41 5.27 cm 1
It is seen that the quantity JLI/Y has the dimension of (velocity)~l and thatN/pg/y
has the dimension of (length)-1, so that they are used in non-dimensionalizing
the pumping rate, the rotation rate and the slick thickness.
Same sample calculations follow:
Diesel 40-weight Bunker C
Disk Immersion Chord C 100 100 100 cm
Slick Thickness d 1.0 1.0 1.0 cm
Dimensionless Thickness d 5.38 5.41 5.27
Rotation Rate GJ 1 0 1.0 1.0 rad sec
Dimensionless Rotation Rate o3 0.148 16.7 147
Dimensionless Pumping Rate
-3
Q (from Figure ) 1.2x10 2.5 60
3 -1
Pumping Rate (per disk) Q 15 277 775 cm sec
14 263 737 gal hr~
95
-------
It can be seen from these values of the pumping rate that the major effect, as
would be expected, comes from the viscosity of the oil, the lower viscosity of
the diesel oil causing a thinner b oundary-layer on the disk and thereby a lower
pumping rate, for the same disk geometry and rotation rate as used for a more
viscous oil. One could, however, suggest that the rotation rate be increased in
order to pump more diesel oil. The theory, in fact, does not impose any limit
on o3 and, thereby, on Q. A practical limit, however, may be expected to pre-
vail, from a consideration of the fact that the disk, being partially immersed
also in water, would also pick up water, whereas the theory as formulated here,
does not take this into account. The test results do indicate this limit for water-
free oil pick-up exists for each of the three oils tested.
COMPARISON OF THEORY WITH EXPERIMENT
Before proceeding with a comparison of the theory with data gathered from the
experimental program it may be well to recall the assumptions and limitations
under which the theoretical model is constructed. The theory essentially
accounts for the vertical lifting of oil from a slick by the viscous shearing
action of a vertically moving surface. Implicit in this formulation is the
assumption that there is a constant reservoir of oil with a uniform and constant
thickness, and that the oil surface is smooth. It is further assumed that the
moving surface preferentially picks up oil rather than water. Thus the limited
scope of the theory does not take into account, except as a boundary condition
where the oil flow turns from horizontal to vertical, the "feeding" of the disk
by the lateral approach of the bulk of the oil slick. Conceivably the oil slick,
without external stimulus, may not flow fast enough under the actions of
gravity, viscosity and surface tension, to sustain the pumping action of the
disk, in which case the assumption of a constant slick thickness approaching
the disk would be violated, and the disk "starves. " The constant reservoir
assumption of the theory can practically be met by moving the oil slick past the
disk so that the latter is always operating in a fresh pool of oil. The question
of water pick-up is disposed of basically by assuming that the disk surface does
not "wet" water while it does wet oil. Any actual departure from this perfect
non-wetting assumption must be established experimentally, as will be dis-
cussed in this section. The effects of a wavy oil slick surface are beyond the
scope of the analysis, and can only, at this stage in the development of the
theoretical model, be assessed experimentally. It may, however, be suggested
that the effects of waves can no doubt be reduced if the displacement of the oil
surface does not result in significant variations in the immersion depth of the
disk.
96
-------
For a gross assessment of the validity of the theory one may refer to Figure 60,
which shows all the data points from the static tests (no current) and to Fig-
ure 61, which shows all the data points from the towed tests. It is seen that the
great majority of the data points fall within the region in the Q ~u> plane bounded
by the theoretical performance lines for an infinitely thick slick and for a thin
slick of dimensionless thickness d = 0.1 (which corresponds to a physical thick-
ness of about 0. 02 cm for all three oils tested). The intermediate theoretical
curve for d = 1 corresponds to a physical thickness of about d = 0.2 cm, so
that most of the tests would be expected to fall above this curve. For the static
tests, Figure 60, the un-flagged data points (for tests with no water pick-up)
for diesel oil mostly fall about the theoretical curve. For the 40-weight oil the
un-flagged data points fall predominantly between the theoretical curves for
d = 1 and d = <». The fairly large number of flagged points, which lie below the
line for d = 1 suggests that the "effective" slick thickness at the disk is less
than the actual (far away from the disk) because of "starvation" - or lack of
proper "priming" of the pump. This effect is more pronounced when one exam-
ines the data from the Bunker C oil tests, wherein very few data points are
un-flagged (without water pick-up). The starvation effect, which is an effective
thinning of the slick near the disk, presumably also promotes water pick-up,
especially if there are actual breaks in the slick surface due to the pumping
action of the disk.
The starvation effects are apparently considerably lessened when there is cur-
rent carrying the oil towards the disks, as is evident in Figure 61, in which
tow-basic test data for 40-weight and Bunker C oils are shown. Two facts are
significant, on comparing Figure 60 with Figure 61. One is the general shifting
upward along the theoretical curves of the test points; the other is the reduced
number of flagged data points relative to the unflagged ones. These two obser-
vations suggest that the primary effect of current is to enhance the priming of
the disks so that they can operate to higher rotational rates than in the static
case before water entrainment sets in.
To see how much effect current has on a portion of Figure 61 is enlarged and
shown in Figure 62 with data chosen for different current values but with a
constant slick thickness, corresponding to d = 14. It is seen that the groups of
data points move up with increasing current, such that they approach the theo-
retical curve for d~= 14 as current increases from 0.25 knot to 2.0 knots.
There is a reversal of this trend as the current increases to 3.0 knots, how-
ever. The reason for such a maximum in current for maximum water-free
pumping is probably that at high currents the slick is pulled away from the disks,
rather than being herded towards the disks at some low but not zero value of
the current.
97
-------
SINGLE DISK, ZERO CUUHENT
FLAGGED SYNBOLS WATEK CONTENT
O DIESEL OIL
40 WEIGHT OIL
D BUNKER 'C'
Figure 60. Comparison of Theory with Experiment - No Current
98
-------
D
a D
-4
Figure 61. Comparison of Theory with Experiment - With Current
99
-------
Q
\ y c
6 7 8 9 10
Figure 62. Effect of Current on Collection at Constant Slick Thickness
100
-------
The agreement with theory at an optimum current for a relatively thin slick
can also be seen in the data shown in Figure 63. This is the case for d = 3.4
(d = 0. 25 inch). At a low current of 0. 5 knot the test data fall considerably
below the theoretical curve for d = 3.4. But as the current increases to 2 knots
the test points come quite close to the theoretical values. Again, as the current
increases past 2 knots, the pumping rate falls back down and water entrainment
sets in.
Short of a complete analysis of the flow field in the oil approaching the disks,
it will not be possible to give a good accounting for the limiting disk rotation
rate at which water entrainment sets in. The level of effort planned for the
present investigation does not permit such a broadened scope of the theoretical
work; so that for the time being one would have to resort to empirically deter-
mined limits to the disk rate for design purposes. An overall examination of
the data in Figure 61 indicates that a limiting value of the dimensionless rota-
tion rate w = 60 should be appropriate for the 40-weight oil, and that w = 100
should result in water-free pick-up of Bunker-C oil. Since no tow-basin tests
were run with Diesel oil it will be necessary to estimate a limiting for it by
inference from the data for the heavier oils. Comparison of data for 40-weight
and Bunker-C in Figures 60 and 61 show that there is an increase by a factor of
about 2 to 3 in the pumping rate when currentprevails. On this basis a limiting
disk rotation rate of o3 = 1 is assigned to diesel oil.
Once a limiting (maximum) is established the maximum pumping ability of a
given disk is set. The total pumping rate that can be achieved by a system of
disks depends then only on the number of disks employed. For compactness
one would want these to be placed as closely as possible along a common shaft.
These must, however, exist a lower limit to the spacing between disks beyond
which adjacent disk surfaces would interfere with each other, with consequent
loss of pumping performance. An estimate of this minimum is made below.
The spacing between disks would be large enough to prevent the oil from filling
the space and reducing the pumping effectiveness of the disks. The minimum
spacing would be given by the widths of the oil layers on the disk surfaces plus
the width of the oil fillet between these layers. The width of the oil layers is
2 6
max
101
-------
.15
0.1
.25" LAYER
40 WEIGHT OIL
6" IMMERSION
FLAG 4" IMMERSION
DOUBLE FLAG = 2" IMMERSION
1.0 1.5 2 2.53 4 5 6789 10
20 25 30 40 50 GO 7080 100
Figure 63. Effect of Current on Collection at Constant
Slick Thickness - Thin Slick
102
-------
and the width of the fillet is not more than 2 Y/pgh . = y (see Figure 64),
where h . is the height of the fillet trough. For v = 18 h
mm 5 yi 10 nmin
or
and
min 9 \pg
i(JL)
9 W/
h = \ /
min 3 Vpg
y, = 6
X
DISK
OIL
max
max
DISK
SURFACE OF SLICK
Figure 64. Boundaries Between Disks
The minimum spacing would then be
6 = 2 5 + y-i = ,,
mm max Jl V Pg
-1 + 3
103
-------
For a deep slick, £ = 2u./Y coC, which is the worst case.
max
With Bunker C the largest value of £ is of the order of 200, and
fa ^
6 = \/- 17201 -1 + 3^2 | = 4.6cm = 1.8 inches
min
Similarly the minimum spacing the thick layers of 40-weight and diesel oils are
calculated to be:
Diesel Oil 0.98 cm or 0.38 inch
40-Weight 3.4 cm or 1.3 inch
It is noted that these minimum spacings are independent of the size of the disk.
This means that the disk immersion chord to spacing ratio can be made quite
large as the disk size is increased. For example, using a spacing of 2 inches
and a disk immersion chord of 50 inches, this ratio is 25.
The significance of this ratio comes in when one compares the performance of
a multi-disk system with a drum of the same diameter and with the same length
in the longitudinal direction. Following the same procedure as with the disk the
following equation for the pumping rate of a cylinder of radius R can be developed:
A comparison with the pumping rate for a disk (immersed to C = 2R) shows that
the two systems should be equivalent when the chord-to-spacing ratio is between
2. 5 and 3. 0. This means that at a ratio of 25 the disk system can pump ten times
as much oil as a drum of the same diameter and length.
104
-------
SECTION X
DESIGN APPROACH
Based on the analysis of Section IX, a design calculation procedure was developed.
Calculations were made covering a wide range of each parameter, and the data
tabulated. From this, performance envelopes were drawn for each of the three
oil types tested. Following on this, specific design recommendations are made,
and finally operational recommendations are made.
PERFORMANCE ENVELOPES FOR THE DISK SYSTEM
The design criteria were based on the non-dimensional disk pumping rate
expression with the following parameters:
1. Dimension-less single disk pumping rate
if
YVY
where
M- = Coefficient of viscosity
Y = surface tension
p = density
g = acceleration of gravity
C = disk chord at immersion depth
Q = pumping rate per disk (both sides)
2. Dimension-less disk rotation rate
105
-------
where
= disk rotation rate
OIL THICKNESS
d
CURRENT
Figure 65. Model Disk
Q expresses the pumping rate on the assumption that the disk pump is "primed"
properly and there is adequate in-flow of oil towards the disk. The flow field
external to the disk which effects this "priming" condition has not been analyzed.
Water entrainment resulting from over-speed is empirically established from the
experimental data in terms of a "critical rotation rate", GO , for each of the
("*T*1 T
three oil types tested.
The incoming volume flow rate of oil per unit width of the oil front in a current
is
where
V - Ud
3
U = current speed
d = oil thickness
If s = spacing between disks, the desired condition for a single pass clean sweep
of the oil would require that
-^- - V = Ud
106
-------
If the gross pumping speed of a disk array system is P.
P = -^ L
s
where
L = length of array
and
N = (to nearest integer) is the number of disks
s
The spacing (s) cannot be arbitrarily small, because oil may completely fill the
space between disks.
The properties of the three types of oil tested are listed below:
Bunker C
Y
H-
P
u/Y
Diesel
28.5
-2
4.2 x 10
0.842
-3
1.48 x 10
40 -Weight
30.0
5.0
0.895
1.67x
-1
10
34.6 dynes cm
50. 6 gm. cm sec.
-3
0.979 gm. cm
1.47 cm sec.
i
-2
pg/Y 2.90x10 2.93x10 2.78x10 cm
3 -1 -1
Using these units, the units for Q and w are (cm. sec. ) and (radians, sec. )
respectively.
The limiting w, for the threshold of water entrainment for the three oils, and the
corresponding Q are:
Diesel_ 40 Wt. Oil Bunker 'C'
i v - - -/ -J 60
crit ^ 'crit.
/jj- 19 ' g Q. J.\ 0.04 30 65
~
max
/
. ~ \
Y V V s C
max.
107
-------
Specimen calculation for 40 Wt. oil
1. to ., = (£ co G) - 60
crit. \V /
crit.
O -
> Qmax. " Y>Y s C
max.
3. Let U =2 knots - 103 cm. /sec.
max
and d = 1 inch = 2, 54 cm.
max
= V = U xd = 262 cm.2 sec.
s / max. max. max.
max
(§)
Q
max.
f- p. /m (Q\
Y V Y Is/
30
: = 0.127
1.67x10 ,72973x262
5. From I/
60 -1
(co C) = = 360 cm. sec.
v ;crit .167
Let co = 2 rad. sec. - 0. 32 revs. sec.
Then c = 180 cm. = 5. 9 ft.
Spacing s = 0. 127 x C = 23 cm. -9.0 in.
108
-------
6. 3 -1
P . . = 50 x 10 gal hr.
design
= 5.25 xlO4 cm.3 sec."1
T _ Pdesign 5. 25 x 1Q4
L ~ ~^- = = 200 cm. - 6. 6 ft.
Q\ 262
max.
(1)
N = L = 200
s 23
Pumping rate per disk
Q s
Q = -' 77- C = 26.2x0.127x180
S v-/
= 6000 cm. sec."1 = 5, 700 gal. hr."1
Total Q = 5, 700 x 9 = 51, 300 gal. hr."1
The important linear dimension with regard to oil pick-up is C, the wetted disk
chord at immersion depth.
This chord dimension geometrically fits a disk diameter of 7.00 ft. and a disk
immersion depth of 1.64 ft.
The above calculations were carried out for a series of current speeds, oil
thicknesses and disk speeds of rotation for all three ©il types, and were
tabulated.
Graphs which form performance envelopes have been plotted from the tabulated
data, and are presented. Figures 66, 67, 68 present plots of (S/C ) versus
current speed for various oil thicknesses for 40 wt. oil, diesel oil and Bunker 'C'
oil respectively
109
-------
oJ
O
CO
MAXIMUM DISK SPACING TO WETTED CHORD RATIO
40 WT. MOTOR OIL S.G. .89
W ,. - 60
crlt.
Q =30
max
CURRENT KTS
Figure 66. Oil Recovery System - Design Parameters
110
-------
MAXIMUM DISK SPACING TO WETTED CHORD RATIO
DIESEL FUEL OIL S.G. .84
W . = 1.0
crit
0.6
0.5
0.4
:s/c)
MAX.
0.3
0.2
Q = 0.04
max
OIL THK. 0.1 IN.
3.0
CURRENT -KTS
Figure 67. Oil Recovery System - Design Parameters
111
-------
s/c
max
0.4
0.3
0.2
0.1
1.0
1
MAXIMUM DISK SPACING TO
WETTED CHORD RATIO
BUNKER C FUEL S.G. .98
W = 100
crit.
Q =65
max
OIL THICKNESS 0. 5 IN.
1.0 IN.
1.5 IN.
1.5 2.0
CURRENT KTS
2.5
3.0
Figure 680 Oil Recovery System - Design Parameters
112
-------
Figure 69 is a plot of disk spacing versus current speed for various oil thick-
nesses for 40 wt. oil. The oil pick-up for all points on the graph are 50,000
gallons/hour with zero water content, so any point is a possible design solution:
Other fixed parameters are disk diameter 7.0 ft., number of disks 9, disk
immersion depth 1.64 ft., and disk rotational speed 0.32 revs/sec. Figures 70,
71, 72, and 73 are similar plots for other fixed conditions and other oils, the
actual conditions being printed on the figures.
Limiting values of disk spacing (s) are as follows:
Oil Type
40 Wt.
Diesel
Bunker 'C'
Limiting (s)-in.
1.3
0.38
1.8
Limiting (s)-in.
(with safety margin)
2.0
0.57
2.7
Design solutions from the performance envelopes described, the following pre-
liminary design recommendations are made.
Table 1. Case 1: Designs of Full Scale Systems for Thick Slick
R 3.5 FT. C 5.9 FT. Q 50,000 Gallons Per Hour
L Ot31
1.0 In. THICK
DIESEL
(0.5 in. slick)
40 WT. SAE
BUNKER 'C1
Q
MAX
CURRENT
1.0
0.04
30
100
2 KNOTS
R.P.S.
0.32
0.06
Q (SINGLE DISK)
5,700
1,435
NO. OF DISKS
58
SPACING
2.72
9.0
2.27 INCHES
SYSTEM LENGTH
(Not including disk
thickness)
13.15
Ref. Fig. 72
Ret. Fig. 1,9
d.()2 FT.
Ref. Fig. 73
113
-------
Table 2. Case 2: Designs of Full Scale Systems For Thin Slick
R 3.5 FT. C 5.9 FT. Q 50,000 Gallons per hour
Total
1mm SLICK
1.0
0.538
40 Wt. SAE
0.541
4.Ob
CURRENT
KNOTS
(SINGLE DISK)
MIN. SPACING
(Based on Meniscus Study) 0.38
NO. OF DISKS 78
MIN. DISK SYSTEM LENGTH 2.5
(Not incl. Disk Thickness)
FRONTAL HERDING WIDTH 168
GAL. PER HOUR
INCHES
FT.
For an operational system it is expected that a compromise system with fixed
disk diameter, number of disks, and disk spacing will be used. Disk RPM and
immersion depth would be made controllable.
FLOW DEFLECTORS
The assumption has been made in the analysis that there is an adequate inflow
of oil towards the disk. The tests indicate that some means should be imposed
on the external field to force oil flow normal to the disk, such as the one
sketched on the following page. (Figure 74).
OPERATIONAL RECOMMENDATIONS
The disk system with a maximum span of 13. 5 ft. should be rigidly attached to
the bow of a tank barge 250 ft. x 44 ft. x 14 ft. 6 in. This size of barge is
required from the craft motions point of view (see Section II). With a capability
of 25, 000 barrels of fuel oil it could operate with a powered disk system for up
to 21 hours, working as an independent unit.
114
-------
I
o
1I
u
co
co
ii
Q
25
20
15
10
DESIGN ENVELOPE FOR 40 WT. MOTOR OIL, S. G. .89
DISK DIA. 7 FT.
NO. OF DISKS - 9
DISK IMMERSION DEPTH 1.64 FT.
DISK REVS 0.32 REVS/SEC.
1.0
\
OIL PICK UP 50,000 GAL/HE.
ZERO WATER CONTENT
AX. SPEED OF
RECOVERY SYSTEM
RELATIVE TO OIL
OIL THK. 0.5 IN.
-SUGGESTED DESIGN POINT
r-S FROM THEORY
r MIN.
1.5
2.0
2.5
3.0
CURRENT - KTS
Figure 69. Oil Recovery System - Design Parameters
115
-------
I
o
II
o
PH
CQ
I
Q
DESIGN ENVELOPE FOR 40 WT. MOTOR OIL,
DISK DIA. 14 FT.
NO. OF DISKS 5
DISK IMMERSION DEPTH 3.28 FT.
DISK REVS. 0.16 REV./SEC.
OIL PICKUP 50,000 GAL/HR.
ZERO WATER CONTENT
MAX. SPEED OF RECOVERY
SYSTEM RELATIVE TO OIL
OIL THICKNESS-0.5 IN.
FROM THEORY
1.0 1.5 2.0 2.5
Figure 70. Oil Recovery System - Design Parameters
116
-------
I
o
A
CO
GO
II
Q
DESIGN ENVELOPE FOR 40 WT. MOTOR OIL, S. G. 0.89
DISK DIA. 3.5 FT.
NO. OF DISKS 18
DISK IMMERSION DEPTH 0.82 FT.
DISK REVS. 0.64 REV./SEC.
OIL PICKUP 50,000 GAL/HR.
ZERO WATER CONTENT
MAX. SPEED OF RECOVERY
SYSTEM RELATIVE TO OIL
OIL THICKNESS 0.5 IN
FROM THEORY
2.0 2.5
CURRENT - KNOTS
Figure 11. Oil Recovery System - Design Parameters
117
-------
DESIGN ENVELOPE FOR DIESEL FUEL OIL, S.G. 0.84
DISK DIA. 7 FT.
NO. OF DISKS 58
DISK IMMERSION DEPTH 1.64 FT.
DISK REVS. 0.60 REV./SEC.
OIL PICKUP 50,000 GAL/HR.
ZERO WATER CONTENT
MAX. SPEED OF RECOVERY
SYSTEM RELATIVE TO OIL
OIL THICKNESS 0.1 IN
SUGGESTED DESIGN POINT
FROM THEORY
I
2.0
CURRENT - KNOTS
Figure 72. Oil Recovery System - Design Parameters
118
-------
25
20
O
£
i i
o
3
Q
15
10
DESIGN ENVELOPE FOR BUNKEE 'C' FUEL. S.G. 0.98
DISK DIA. 7 FT.
NO. OF DISKS 35
-DISK IMMERSION DEPTH 1.64 FT.
DISK REVS. 0.06 REV./SEC.
OIL PICKUP 50,000 GAL/HR.
ZERO WATER CONTENT
MAX. SPEED OF RECOVERY
SYSTEM RELATIVE TO OIL
SUGGESTED DESIGN POINT
OIL THICKNESS 0.5 IN
3.0
CURRENT - KNOTS
Figure 73. Oil Eecovery System - Design Parameters
119
-------
CURRENT
Figure 74. Disk with Deflectors
120
-------
When working in a spill of crude oil or Bunker 'C' the disk-barge system would
work without any herding arrangements. In a spill of oil equivalent to SAE
40 wt. motor oil it might have to operate within some sort of containment
system, and would also probably be equipped with herding booms of its own as
shown in the sketch below: (Figure 75).
120 FT.
DIRECTION
OF TRAVEL
Figure 75. System with Herding Booms
In a spill of light diesel oil, the disk-barge system would probably have to be
anchored at the apex of a much larger herding boom system as shown in the
sketch below: (Figure 76). This is because diesel oil has such a high spreading
rate, and in very thin slicks can only be picked up at a slow rate with high water
content.
WIND AND
CURRENT
Figure 76. System with Anchored Booms
121
-------
SECTION XI
REFERENCES
1. Concept Development of a Heavy Duty Oil Containment System for Use
on the High Seas.
Parti, Final Report, Volume I, June 1970. Prepared for U.S. Coast
Guard Headquarters, Washington, D.C. Under Contract No. DOT-CG-
04492-A by Atlantic Research, Costa Mesa, California.
2. Principles of Naval Architecture by J.P. Comstock. Published by the
Society of Naval Architects and Marine Engineers, 74 Trinity Place,
New York, N. Y. 10006, 1967.
3. Proposal for "Recovery of Floating Oil - Rotating Disk Type Skimmer"
AR/SD Proposal No. 2-744, Addendum A, February 1970. Prepared
for United States Department of Interior, Federal Weight Quality
Administration, Washington, D.C. in Response to RFP No. WA 70-23.
4. "Oil Spillage Study Literature Search and Critical Evaluation for
Selection of Promising Techniques to Control and Prevent Damage"
Report No. AD 666289, Battelle Memorial Institute, Richland,
Washington, 20 November 1967.
5. Aeromarine Test Facility, Model Towing Basin and Hydrodynamic
Laboratory. Technical Information, General Dynamics, San Diego,
California.
Pending Publication
"Concept Development of a Powered Rotating Disk Oil Recovery System",
by A. C. Connolly and S.T. Uyeda, in course of preparation for the 1971
Conference on Prevention and Control of Oil Spills scheduled to be held
in Washington, D.C. during June 15-17, 1971
123
-------
SECTION XII
SYMBOLS
W Disc rotational speed - rads/sec.
R Disc radius
D Immersed depth of disc
r Some disc radius
Q Angle subtended by line joining point where r intersects oil
surface and center of disc, and the vertical
X Horizontal distance from point where r intersects oil surface
and center of disc
d Oil depth at disc
C Disc chord at the immersion line
6 Boundary layer thickness of oil on disc
dV
F , F = -JJL dx dz Shearing forces
^ Qy
g Acceleration due to gravity
p. Viscosity of oil - gm. cm sec."*
Q Density of oil at edge of boundary layer
FM = - H- ( ) 6 h^ dx Shearing force
hr Height of oil at edge of boundary layer above static level
Surface tension of oil - dynes. cm"*
Q Volume of oil picked up by both sides of disc per unit time
~L Length along water line where oil is picked up L = 2 f - X J
S Distance from disc center line to point where boundary-layer
thickness is zero
125
-------
6max
Q Dimensionless disc pumping rate
mm
Q
C
W Dimensionless disc rotation rate
= ~ij~ w c
d Dimensionless slick thickness -
h__. Is the height of the oil fillet trough between two closely spaced
discs
Minimum disc spacing
mm ,.
discs
V Volume flow rate of oil per unit width of the oil front in a current
U Current speed
s Spacing between discs
P Gross pumping speed of a disc array system
L Length of disc array
N Number of discs
126
-------
SECTION XIII
APPENDICES
Page No.
I. Material Evaluation Basic Data 128
II. Laboratory Results of Oil Properties 134
127
-------
APPENDIX I
MATERIAL EVALUATION BASIC DATA
128
-------
PHASE I MATERIAL EVALUATION
\V;der Wetted Samples
Water Wetted Surfaee.s l\1g Oil/sq in Dry lia.si.s
Teflon
Diesel 9.6
10.4
14.G
13. 3
10.0
8.8
11.8
8.2
7.6
8.1
7. 7
7.3
Median 9.8
Bunker C 384
337
409
301
344
404
423
552
388
566
639
480
Median 408
Crude 132
130
85
140
164
117
107
_
125
168
127
12]
1\)1_\ earbonule
(.». 1
7. 4
6. 5
6. 5
4.6
4. 1
3. 5
5. 2
2. 5
4. 9
3. 1
3. 0
4. 8
206
154
174
196
186
210
212
475
361
370
418
-
210
81
105
89
97
115
105
122
88
98
93
114
119
Polypropylene
2.0
2.4
2.1
1.6
6. 1
11.6
6.4
7.0
3.5
6.6
5.8
8.1
6.0
391
314
432
603
570
243
262
618
344
370
266
483
412
177
126
122
174
145
-
124
209
19G
194
277
361
Pol3relhylene
17. 5
61.7
19.4
16.5
17.6
14.0
15.9
17. 3
16. 0
17.1
17.5
-
17. 3
594
378
510
490
387
529
450
494
517
566
622
681
523
309
243
225
275
345
240
171
246
302
249
273
409
Neoprcnc
20.4
15. 1
19. 0
25. 2
19.4
13.4
19. 3
-
11.6
10. 1
11. 1
10. 5
15.1
437
507
452
314
237
548
488
302
438
528
439
497
448
294
212
269
225
268
246
252
364
320
280
223
203
Al
1. 9
.6
3. 1
3. 3
2.4
3.8
2. 8
3. 1
2. 2
2. 3
2.1
3. 1
2.6
536
235
341
449
459
382
263
362
527
492
333
572
415
211
213
185
245
140
117
106
184
322
218
146
253
Mild
Steel
3. 2
3. 0
4.8
4. 6
3.6
5. 3
4. 2
2.3
3. 0
2.3
3.2
3.6
3.6
422
765
354
529
232
452
350
418
320
278
326
306
338
248
205
169
210
140
212
-
121
35
185
94
SS
5. 4
2.8
5. 6
3.4
4. 5
4.8
6.8
2.5
3.4
3. 3
2. 9
2.6
3.4
527
356
427
319
357
222
246
296
325
271
382
369
322
84
159
151
172
222
243
196
112
150
128
90
190
177
285
259
129
-------
Walcr Welled Samples
Walcr Welted Surfaces 7i Oil Picked t'p
Teflon Polycarbonate
Diesel
Median
Bunker C
Median
Crude
77.6
73.1
61.2
72.8
71.8
48.6
25.0
72.8
76.2
73. 7
82.2
74.1
73.3
98. 7
98.9
98.7
97.9
98.4
98.9
98.9
97.4
97.2
98.4
99.0
98.7
98. 7
95.1
96.5
96. 0
95.2
95.8
94.4
93.0
-
96.3
96.8
95.9
96.8
47.
46.
34.
47.
29.
48.
38.
38.
48.
58.
56.
69.
47.
96.
96.
95.
98.
96.
98.
99.
98.
99.
98.
98.
98.
98.
93.
94.
96.
95.
96.
93.
94.
93.
90.
95.
96.
95.
2
0
4
8
4
6
8
9
1
2
2
8
9
6
3
1
5
6
1
3
9
0
3
7
2
5
3
9
0
0
3
5
1
5
4
1
6
7
Polypropylene
26.
44.
34.
33.
20.
35.
28.
46.
12.
15.
19.
11:
31.
97.
99.
98.
96.
99.
94.
96.
98.
97.
97.
97.
98.
98.
95.
91.
92.
98.
91.
91.
92.
93.
97.
95.
96.
90.
4
9
4
1
1
1
4
7
1
8
8
1
0
6
1
7
3
2
7
3
3
8
9
1
5
1
0
1
6
7
9
3
8
7
5
6
9
8
Polyethylene
90.
95.
95.
98.
96.
93.
96.
95.
96.
91.
93.
90.
96.
96.
96.
99.
99.
99.
99.
99.
99.
99.
98.
99.
99.
99.
97.
96.
97.
96.
98.
96.
95.
97.
97.
-
97.
98.
6
7
7
0
1
3
7
6
9
8
8
8
1
6
1
8
1
4
3
5
2
0
8
2
1
3
1
2
4
6
5
7
7
6
0
2
7
Ncoprenc;
94.6
88. 6
80. 7
87. 8
89. 3
84.4
87.5
-
62.5
76.2
57.8
68.4
80. 7
97.6
96.8
98.4
96.3
94. 9
98. 3
98. 7
96.6
97. 9
98. 5
98. 9
98. 2
98.4
97. 3
95. 0
93. 6
96. 5
96. 6
93. 0
95. 7
95. 3
94.4
96.4
95. 0
94. 2
Al
37.6
27. 2
-
43. 7
47. 2
23. 7
41.6
39.6
28. 9
43.8
25. 9
42.6
37.6
98. 0
95. 5
97. 3
98. 1
96. 3
97.4
96. 8
96. 6
98. 1
97. 2
97. 2
97. 9
97. 7
93. 5
95. 7
93. 5
96. 2
92. 2
92. 5
91. 7
95.4
97. 3
91. 5
96. 0
97. 0
Mild
Steel
18. 1
16. 1
26. 1
24. 3
25. 7
26. 3
26.4
15. 1
25. 1
15.6
20. 7
21. 8
24. 2
97. 3
97. 8
97. 5
98. 5
96.4
98. 1
97. 8
98.0
96. 9
94. 8
90. 6
95. 9
97. 7
97. 4
94. 9
96. 0
92. 4
92. 1
96. 3
-
-
93. 7
90. 2
95. 0
<)3. 7
SS
2S. -1
21. S
37. 1
17. S
27. 2
O v C,
,J -^ . O
43. 0
13. 3
14.4
16. 0
14. 1
13. 3
22. 5
98. 5
97. 9
98. 2
97. S
98. 1
90. 4
98. 3
90.4
90. 9
95. 4
95.0
on. n
9>. 0
So. -.
no. ii
six 5
92. ;
94. 3
95. 0
95. 0
9.1. 2
96. s-
93. 7>
<):;. o
9(i. :;
Median
90. 0
95. 7
97. 2
130
-------
PHASE II MATERIAL EVALUATION
Oil Welted Samples
Oil Welled Surfaees Mf; Oil/sc| in Dry Basis
Teflon 1
Diesel 13.6
12.6
12.9
13.6
11.9
10.0
14.3
10.7
12.9
12.5
13.0
10.5
Median 12.8
Bunker C 700
661
506
874
685
694
719
743
675
578
611
736
Median 710
Crude 345
347
356
315
395
368
343
469
510
473
475
456
'olycnvbonnlc
3.
6.
6.
3.
7.
5.
4.
14.
11.
12.
12.
12.
6.
680
743
708
721
829
815
820
691
742
671
703
720
721
398
387
421
473
427
417
415
380
505
441
513
452
1
0
2
6
3
4
6
3
0
2
7
3
8
Polypropylene
21.
17.
20.
20.
24.
24.
29.
30.
28.
25.
26.
25.
24.
693
649
643
758
746
496
584
664
657
665
677
586
661
378
378
365
398
373
374
388
354
508
573
505
540
9
4
7
9
5
4
3
3
7
4
8'
9
6
Polyethylene
16.
18.
18.
21.
18.
20.
24.
20.
19.
21.
20.
21.
20.
586
738
615
747
677
614
635
693
557
651
623
517
629
493
541
525
416
399
391
437
403
544
542
471
580
9
1
4
1
9
5
5
5
3
2
6
3
6
Neoprcnc Al
25.
24.
29.
23.
20.
23.
24.
18.
17.
19.
25.
24.
23.
677
633
728
662
611
716
865
717
669
650
668
755
673
523
547
497
534
504
565
553
588
638
498
579
559
4
2
4
6
3
0
1
6
8
3
8
1
9
23. 8
23. 3
26. 3
22.4
22. 0
26.9
30. 7
23. 5
24. 5
23.8
21. 3
24.1
24. 1
691
532
570
614
600
553
709
767
605
697
640
537
610
357
458
396
437
385
338
485
369
376
43-1
4M
416
Mild
Steel
15. 9
19. 8
17.6
20.6
17. 9
16. 7
20.4
22. 3
23.0
17.4
22. 3
19. 7
19.8
590
586
547
638
697
661
544
469
561
569
561
526
565
498
469
412
518
579
476
481
510
508
ISO
517
122
SS
18. 7
17.4
16. 9
18.8
15.8
-18. 3
19.4
19. 1
13.8
20.0
14. 7
22.4
18. 8
688
672
711
732
569
657
640
541
454
536
567
493
656
459
470
46 S
465
167
134
517
5M
5-1 fi
545
ISO
-172
Media
3K3
482
556
'105 -I ill '175
131
-------
Oil Welted Samples
Oil Wetted Surfaces % Oil Picked Up
Teflon P
Diesel 84. 7
83.6
85.4
84. 1
83.0
79. 7
87.2
70. 9
69. 9
75.1
79. 1
69. 9
Median 81. 6
Bunker C 99. 9
99. 7
99. 9
99. 9
99. 9
99. 9
99. \
99.8
99.8
99. 8
99. 8
99.8
Median 99. 8
Crude 99. 4
89. 2
98.5
99. 3
99.5
99. 2
98. 7
99. 6
99. 1
99. 0
99. 0
99. 0
Median 99. 3
'olycarboniile
38. 3
54.9
59. 1
50. 5
57.4
47. 1
47. 6
77. 6
71. 3
78.4
74. 5
72. 1
64.4
99.6
99. 9
99.9
99.8
99.9
99.8
99.6
99. 9
99. 6
99.8
99.9
99.8
99.8
98.4
98.4
98. 8
98. 9
98. 7
98.2
98. 5
98. 2
99. 0
99. 0
99. 3
98. 3
99. 8
Polypropylene:
51.9
98.0
50.2
49.9
54.5
52.4
55. 2
59.5
56.4
52.1
54.5
57. 3
53.4
99.8
99.8
99.8
99.8
99. 8
99.8
99.7
98.7
99.6
99.6
99. 7
99. 6
99. 7
98.4
98.9
98.9
98.5
98.4
98. 5
98.6
98.5
99. 0
99. 3
98. G
99. 0
98. 9
Polyethylene
91.4
91.8
89.2
95. 7
91.1
95. 7
93.6
96. 9
85.4
86.2
80. 2
91.4
91. 6
99.8
99.9
99.8
99. 9
99. 8
99.8
99.7
99.8
99.8
99.5
99.8
99. 7
99.8
99.6
99. 5
99. '2
99.2
99.4
98.8
98. G
98. 7
99. 1
98. 8
99.0
99. 0
99. ]
Ncoprenc
96.8
96.8
96. 3
96.6
95.0
95. 3
94.8
98. 1
94.8
96.0
93.8
94.3
96.4
99.8
99.7
99.6
99.7
99.6
99.6
99.5
99.8
99.4
99.5
99.6
99.4
99.6
98.9
99.4
99.4
99.2
98.7
99.2
99.5
99. 3
99.2
99. 5
99.4
99.4
99.-1
Mild
Al Steel SS
93.2 89.3 S3. 9
92.7 88.7 S4.2
9]. 3 85.2 83.0
91.7 86.2 88.3
91.8 92.8 83.4
93.0 88.9 8G.1
92. 9 87. 7 85. 3
87.2 82.4 95.0
91.3 97.3 85.9
93.3 86.6 89.7
91.1 9], 2 SG.5
87.3 81.8 91.9
92.2 88.7 87.1
99.9 99.8 99.8
99.9 99.8 99.8
99.9 99.8 99.8
99.9 99.7 99.8
99.9 99.8 99.9
99.9 99.8 99.8
99.9 99.9 99.8
99.9 99.8 99.8
99.9 99.7 99. G
99.9 99.7 99.6
99.9 99.7 99.7
99.9 99.7 99.6
99.9 99.8 99.8
99.3 99.6 99.4
99.2 99.4 99.4
99.3 99.6 99.3
98.7 99.4 99.4
99.2 99.6 98.7
99.3 99.5 99.6
99.3 99.3 99.5
99.3 99.4 98.9
99.2 99.4 98.9
99. 2 99 4 98 8
99.4 99.4 99.2
99.2 99. 5 98.6
99. 3 !)!),4 99.3
132
-------
PHASE III MATERIAL EVALUATION
ALUMINUM EVALUATION APPENDIX I
Al Pick-up Vs. Varying Concentrations of Bunkers Diesel
Bunker C
Median
610
90/10
75/25
% Oil Dry Basis
62. 5/3Y. 5 50/50
32. 5/62.5
.25/75
310
133
Mg/Sq In Dry Basis
78. 7
47. 7
38. 0
27. 0
Diesel
99.
99.
99.
99.
99.
Median
99.9 99.
8
7
7
7
6
7
Al
99.
99.
98.
99.
98.
99.
1
1
6
3
9
5
Wt Pick-up/Sq
98.
98.
98.
98.
99.
98.
3
8
7
6
1
7
In Varying
96.
97.
96.
97.
95.
96.
6
3
3
1
9
6
Concentrations
95.
93.
94.
95.
96.
95.
Bunker C -
5
7
9
0
4
3
- Diesel
94.
94.
94.
94.
, 93.
94.
7
2
7
7
7
6 92. 2
311
295
288
339
333
309
161
129
130
166
133
133
64. 2
73. 2
80. 9
76.4
82.0
81. 3
45. 9
48. 2
47. 1
44. 0
53. 5
51.5
44. 3
37. 0
36. 5
38.9
33. 3
40. 3
28. 3
26. 6
26.4
28. 8
24.8
29.0
24.1
133
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APPENDIX II
LABOBATORY RESULTS OF OIL PROPERTIES
TRUESDAIL LABORATORIES, INC,
1EMISTS MICROBIOLOGISTS ENGINEERS
'ESEARCH DEVELOPMENT TESTING
Atlantic Research
3333 Harbor Blvd.,
CLIENT Costa Mesa, California 92626
Attention: Mr. Tom Fralia
SAMPLE 10 Oils as shown
P.O. No. 1011-T
INVESTIGATION Determination of viscosity, surface tension and density.
4ID1 N. FIGLJCHOA STREET
LOS ANGELES yOOCl
AREA CODE 213 225-156-
CABLE TRUELA8S
DATE September 15, 1970
RECEIVED September 3, 1970
LABORATORY NO. 104561
Sample
Identification
Diesel
75/25 C/Diesel
25/75 C/Diesel
Crude
62.5/37.5 C/Diesel
Bunker "C"
from tank
Bunker "C"
50/50 C/Diesel
90/10 C/Diesel
35.5/62.5 C/Diesel * >-''
< fff
RESULTS
/iscosity @ 25°C
Centistokes
4.2
490.
43.1
2458.
107.9
7746.
5056.
80.2
1073.
U «.l
Surface Tension @ 25
dynes/cm
28.5
30.0
28.4
31.7
29.7
35.2
34.6
29.5
31.4
28.8
Density
@ 25°C
0.8420
0.9393
0.8701
0.9561
0.9260
0.9812
0.9790
0.9045
0.9603
0.8862
Respectfully submitted,
TRUESDAIL LAllORATORIES, IKC.
>-
A. H. ,Zalmor, M.S.
Chief'chemist
^Tliis rcjjort npi>lii-j only tn tlir s.iinplr, ' 01' ^.lIn[>l^^, invriti^.tird nncl
idciuicul or Einiilar proclucn. As a immi.il |5iolcc(iou In clu'nls, ili
oc iirci s'.ai il/ indir \tivr of tlir qu
Mir anil lh''si- I.al'or.Honi'.i, this r
for the exclusive u^c of rhr clnjlt lo \vhoiil U is .nldn ssi'il and upuii the c-i.ndnii'ii th.it it n not to I'c list
advertising or jitiblicity innttvi witliout pilot wintcti autlKH i/at IOH ftoin tiifsc L.djoi .tint ii s.
134
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1
Accession Number
w
5
2
Subject Field & Group
05G
SELECTED WATER RESOURCES
ABSTRACTS
INPUT TRANSACTION FORM
Organization
Atlantic Research, Marine Systems Division
Costa Mesa, California 92626
Title
RECOVERY OF FLOATING OIL: ROTATING DISK TYPE SKIMMER
10
Authors)
16
Project Designation
_EPA, WQR Contract No. 14-12-883
21 Note
22
Citation
23
Descriptors (Starred First)
*0il, *0il Wastes, *0ily water
25
Identifiers (Starred First)
*0il Recovery, *Rotating Disks, Experimental Model, Floating Oil
27
Abstract
Laboratory tests of disc materials in oils ranging from light diesel to Bunker
'C' indicated that aluminum was the best overall. Experimental tests on model discs
in still water established baseline performance data and understanding of scaling
effects. Established that oil starvation between discs is a problem, but that percen-
tage of water in recovered oil is less than 2% except for Bunker 'C' oil, and' other
oils in 2mm thickness slicks. Experimental tests of multiple discs in a towing basin
established the effects of current and disc spacing, and showed that the rotational
velocity vector in the fluid should be in the same direction as the current flow.
Non-breaking waves have little effect on oil pick-up rate. The design method developed
by comparison between theoretical analysis and experimental data shows that the over-
all size of the disc unit would be 7 foot diameter by 12 foot for recovery of 50,000
gallons per hour.
Abstractor
S. T.
Institution
Atlantic Research Corp.
WR:102 (REV. JULY 1969)
WRSI C
SEND. WITH COPY OF DOCUMENT,
O: WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON. D. C. 20240
* GPO: 1 970-389-930
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