Note: Descriptions are shown in the official language in which they were submitted.
1063039
Background of the Invention
This invention relates to methods and equipment for oil
spill recovery and more particularly, it concerns an unique sea-
going vessel capable of lifting an oil spill or slick from the sur-
face of sea water, separating the oil from the sea water and storing
the recovered oil temporarily for transfer to a larger vessel or
storage facility in a highly efficient manner.
During the past decade, numerous efforts have been made
to develop equipment and techniques for the containment and recovery
of oil spills at sea resulting either from the collision of oil
transporting ships or accidents in the drilling and operation of off-
shore wells. Although many significant technological developments
have resulted from these efforts, the presently intense exploration
for sources of petroleum products at remote point~ of the globe will
obviously increase tonnage of petroleum products to be transported
or handled at sea. The increased likelihood of oil spills attend-
ant to these activities, therefore, creates a need for oil spill
containment and recovery capabilities far in excess of the current
state of the art. For example, the type of equipment most commonly
used at the present time incorporates one or more oleophilic endless
belts extending forwardly of a supporting barge and which operate to
lift an oil slick from the surface of ~ea water for transfer in the
belt to a wringing device and storage in tanks on the barge. While
such equipment has shown promise in calm water, it is not efficient
in choppy waters nor is a vessel capable of supporting such equip-
ment sufficiently seaworthy for effective operation in unprotected
Waters. Also the speed at which this type of equipment can operate
is limited by the high percentage of sea water picked up with the
oil thus requiring frequent interruptions to empty the tanks of the
recovery ve88el. In addition, such equipment i8 prone to frequent
breakdowns as a re~ult of debris interfering with operating compon-
ents of the sy8tem.
- 2 -
.. ~ .
-,.-. - .. - - - . - ... ~.. , ".... .. ... ..
- : . ,: . : :.
. . . , . . . , . ~ .. . .
1063039
Another class of oil spill recovery equipment in current
use employs a floating suction intake or weir by which oil floating
on the surface of sea water is essentialy decanted and pumped to
storage tanks. This type of equipment is both inefficient in
choppy waters and is particularly vulnerable to breakdown due to de-
bris entering the suction system. In another form of apparatus of
this general type, an adjusted weir is provided at the base of the
U-shaped vessel such that as the vessel is advanced through an oil
spill, a wave of oil-water mixture builds up against the weir with
the oil spilling over and water passing under the weir. Not only
are large amounts of water picked up with the oil, thus reducing the
efficiency of such equipment, but height adjustment of the weir to
avoid interference by floating debris makes difficult a complete
collection of the surface oil slick. Also it will be appreciated
that the use of such a device in other than calm water is accompan-
ied a significant reduction in efficiency due to a collection of
large amounts of water which is tantamount to a significant reduct- `
ion in collection efficiency.
These exemplary types of equipment in current use are by
no means all inclusive of the various approaches that have been taken
to the problems associated with oil spills. Experience with these
types of devices, however, indicates a critical need for increased
speeds of operation; capability for efficient operation in rough or
choppy waters; capability for handling floating debris in the oil
without potential damage to the equipment; increased efficiency in
the separation of the floating oil slick from sea water to minimize
energy requirements for fluid handling; increased oil storage capa-
city in the recovery vessel to avoid operating interruptions for the
transfer of recovered oil to a storage vessel; and increased mobil-
ity from the standpoint of both transporting the recovery equipmentto the 8ite of the spill and from the standpoint of effective recov-
ery operation at the spill site.
,, ,., . , ... .. . : - .~ , :
:. : . . . . . ; - .
- , ~ . , : ,: . , -
1063039
Summary of the Present Invention
Broadly speaking the present invention provides an
oil spill recovery vessel comprising: a pair of transversely
spaced longitudinal hulls each having a plurality of
discrete internal chambers to establish buoyaney tanks and
storage chambers; means for opening the bottoms of the storage
chambers to allow ingress and egress of liquid to and from the
storage chambers;and means for picking up a mixture of oil and
water between the hulls and for introducing the mixture to the
top of the storage chambers thereby to effect in the chambers a
layer of oil superimposed above water until a sufficient quantity
of oil has been introduced into the chambers to displace the
water through the bottoms of the chambers, the last mentioned
means including a pair of transversely extending, counter-rotatable
cylindrical drums spaced longitudinally to establish a gap
between the peripheries thereof, both the drums being movable
from an elevated inoperative position when the storage chambers - -
are empty of liquid to a lowered operative position so that the
peripheries of both drums will be in contact with the surface
of water in which the hulls are floated when the bottoms of
the storage chambers are open, the space between the hulls being
unobstructed except for the drums at and below the surface of -:
water.
In the operation of the vessel, the vessel is first
floated to the site of an oil spill in a light condition; that
is, with the cargo chamber valves closed and empty of ballast so
that the cargo chambers at this time also contribute to the ~ ~:
buoyancy of the vessel. On reaching the spill, the cargo chamber :
valves are opened to flood the cargo tanks with sea water thereby
increasing the draft of the vessel until the lower peripheral
portion of the counter-rotating pick-up drums are submerged -
slightly beneath the surface of the oil slick. The vessel is
ywl/~ ~ 4
.E~ ,
. . - . ~
- - . : . - ..
.
-- ~063~39
then advanced through the oil slick with the drums rotating in
opposite directions and such that tangential movement of the
drum peripheries at the gap between them is upward. As a result
of liquid adhesion to the drum peripheries in combination with
the counter-rotating peripheral movement of the drums, oil or a
mixture of oil and sea water is advanced over the top of each
drum and directed to the flooded cargo holding chambers by the
aforementioned scavenger blades and trough-like ducting. Because
of its lower specific gravity, the oil delivered to the cargo
holding chambers will float on the sea water with which the
holding chambers have been ballasted to a head slightly above
the level of sea water on the hull exterior. As additional oil
is fed to the upper portion of each of the cargo chambers,
however, it will displace sea water downwardly through the open
valves in the bottom of these spaces or tanks. Accordingly, an
effective separation of oil and sea water occurs within the cargo
- chambers such that their capacity for retaining the recovered
oil spill is maximized. Once the tanks are filled with oil, of
course, the ballasting valves will be closed and the oil
transferred to a larger capacity storage vessel.
ywl/~ ? _ 5 _
B
--` 106303~
Other objects and further scope of applicability of the
present invention will become apparent from the detailed descrip-
tion to follow taken in conjunction with the accompanying drawings
in which like parts are designated by like reference numerals.
Brief Description of the Drawings
Fig. 1 is a plan view of the oil spill recovery and con~
tainment vessel of the present invention;
Fig. 2 is a side elevation of the vessel shown in Fig. l;
Fig. 3 is an end elevation of the vessel shown in Figs.
1 and 2;
Fig. 4 is a longitudinal cross-section taken on line 4-4
of Fig. 3;
Fig. 5 is a fragmentary perspective view illustrating the
oil scavenging and transfer ducting system incorporated in the ves-
sel of the invention; and
Fig. 6 is a perspective view showing one method of employ- -
ing the vessel of the invention to recover an oil spill. -;
Detailed Description of the Preferred Embodiment
As shown in Figs. 1-3 of the drawings, the oil ~pill re- -
covery and retention vessel V of the present invention is in the na-
ture of a catamaran having a pair of transversely spaced longitudin-
al hulls designated generally by the reference numerals 10 and 12,
respectively. Each of the hulls is of generally rectangular cross- -~
section to establish a deck-like top wall 14, essentially planar in-
board and outboard walls 16 and 18, respectively and a flat bottom
20. As shown most clearly in Fig. 1, the longitudinal configuration
of each of the hulls 10 and 12 is symmetrical about a transverse me-
dial line and further that the opposite end walls 22 and 24 of each
hull are established by es~entially planar vertical walls disposed
at an angle of approximately 60 with re~pect to the longitudinal
center-line of the ve8sel. Although the aforementioned angle in it-
8elf iB not critical, it will be noted that the direction of end
- 6 -
~063039
wall inclination with respect to the vessel length is opposite in
the two hulls 10 and 12 to establish a funnel-like or converging
hull confirmation extending from the outboard side wall 18 to the
inboard side wall 1~ at opposite ends of the vessel. The vessel
hull structure is physically integrated by a plurality of transver-
se beams 26 extending between and interconnecting the two hulls 10
and 12 near the upper portion of each. Conventional deck screening
supported by the transverse beams 26 extends the top walls 14 of
the hulls to provide a working deck circumscribed by appropriate
guard rails 27.
Although it is contemplated that the vessel may be equip-
ped with its own source of marine propulsion and steering, the dis- ~~
closed embodiment is in the nature of a barge or raft adapted to be
advanced longitudinally by towing or pushing vessels such as conven-
tional tug boats T. To this end, the endmost of the transverse beams
26 at opposite ends of the vessel are fitted with V-shaped bumpers 28
to accommodate a pushing tug boat T for advancing the disclosed ves-
sel in either direction. Steerage of the vessel when pushed by a
single tug boat in this manner is effected by the tug boat steerage
system by way of snubbing lines 30 extending from post bollards 32
at the extreme ends of each of the hulls 10 and 12. In some instan-
ces it may be desired to pull the vessel using one or more towing
tug boat~ in which case the post bollards will facilitate this form
of propulsion.
It will be appreciated that each of the hulls 10 and 12
can be constructed using conventional materials and assembly techni- -
que3 to provide a substantially fluid tight enclosure of a strength
commensurate with the requirements of sea-going hull structures. In
accordance with an important feature of the present invention, how-
ever, it will be noted that each of the hulls 10 and 12 are divided
longitudinally by tran8ver8e walls or bulk heads 34 (Figs. 1 and 2)
to e8tablish in the disclosed embodiment five discrete fluid cham-
-- 7 --
- ~ :
', : '' . ' ': , ': '~
.
1063039
bers 36, 38, 40, 42 and 44. Such chambers provide in each hull al-
ternating buoyancy tanks (36, 40 and 44) and cargo holding chambers
or tanks t38 and 42). Although each of the interior chambers is pro-
vided with a hatch closure 46 of sufficient size to enable access to
the interior of each chamber, it will be noted that the cargo holding
chambers 38 and 42 are also provided with flooding or ballasting val-
ves 48 in their bottom wall 20 and adapted to be actuated by approp-
riate means such as hand wheels 50 accessible at the deck of the ves-
sel. The importance of this interior hull ~tructure will become more
apparent from the description to follow.
It is to be noted that while no pro~ision is shown in the -~-
drawings for ballasting the buoyancy tanks 36, 40 and 41, it is con-
templated that these tanks may be equipped with conventional ballast
valves and pumps to enable controlled adjustment of vessel draft and
freeboard. Such equipment is not essential to operation of the ves- ~ ~
sel nor to practicing the invention, and has been omitted in the in- ~ -
terest of clarity.
As shown in the drawings, a pair of cylindrical drums 52
and 54 are carried by axles 56 and 58, respectively, the respective
axles in turn being journalled at opposite ends in bearing blocks 60
and 62 positioned in deck wells 64 in each of the hulls 10 and 12
near the inboard walls 16 thereof. As shown in Figs. 1 and 4, the
cylindrical drums 52 and 54 span fully the space between the inboard
walls 16 of the hulls and are of such a diameter that the lower per-
ipheral edge of each drum is elevated substantially about the bottom
20 of the hulls 10 and 12. The bearing blocks 62 which support opp-
osite ends of the drum 54 are fixed longitudinally relative to the
hulls 10 and 12. However, the bearing blocks 60, on which the drum
52 is rotatably supported, are ad~ustably positioned for fore and
aft movement by adjustment of feed screws 66. In light of this or-
ganization of the bearing blocks 60, it will be appreciated that the
gap between the periphery of the drums 52 and 54 may be varied from
1063039
a position of contact with each other to a spacing of several
inches.
Each of the drums 52 and 54 is adapted to be rotated in-
dependently of each other in the disclosed embodiment by internal
combustion engines 68 and 70, respectively. Although the drive tra-
nsmission by which the output of each of the internal combustion en-
gines is only generally illustrated in the drawings, it is preferred
that the transmission include an hydraulic pump 72 coupled directly
to the output shaft of each of the internal combustion engines for
supplying hydraulic fluid under pressure to a hydraulic motor 74
coupled by a spline connection (not shown) directly to the axle 60
and 62 of the respective drums. The transmission of motive force from .
the pump 72 to the motor 74 for each drum 52 and 54 is regulated by
appropriate hydraulic control components 76 and 78. The control com-
ponents are preferably positioned for access from a command bridge
80 extending between the hulls 10 and 12 and elevated above the drums
52 and 54. Although complete detail of the drive system for the
drums 52 and 54 is not shown in the drawings, it will be appreciated
by those skilled in the art that the speed and direction of rotation
of the drum 52 may be controlled by manipulation of the control unit
76 whereas rotational direction and speed of the drum 54 may be con-
trolled by manipulation of the control console 78. Also, adjustable
fore and aft movement of the drum 52 and its drive motor 74 may be
accommodated very easily in the di~cloæed system by flexible hydrau-
lic fluid conduits extending between the pump 72 and the motor 74.
As shown most clearly in Figs. 4 and 5 of the drawings,
associated with each drum 52 and 54 is a scavenger or scraper blade
and oil distribution trough as8embly generally designated by the ref-
erence numerals 82 and 84. Each of the a~semblies 82 and 82 is id-
entically constructed to include an inclined scraper blade 86 extend-
ing the length of the associated drum 52, 54 and displaced from the
point of the narrowest gap between the drums by approximately 120.
. .
. . ~ . , . ,~ . , .
1063~39
This angular displacement or location of the blade 86 with respect
to drum rotation enables liquid on the surface of each of the drums
to flow by gravity along the inclined blade 86 and into a trough-like
distributing duct 88 as shown most clearly in Fig. 4. To avoid the
possibility of sparking, the blades are preferably formed or coated
with a resinous material such as teflon though other non-sparking
materials such as aluminum may be used. The duct 88 is divided by a
central baffle 90 and extends to an opening 92 through the top of
each of the cargo storage chambers 38 and 40 in the respective hulls
10 and 12. It is to be noted further that the location of the open- -
ings 92 are located as remotely as possible from the flooding or bal-
lasting valves 48 in the chambers 38 and 42. A coarse screening or
grating 94 extending across the distribution trough 88 prevents the
admission of debris to the tanks 38 and 42.
The operation of the vessel thus described may now be
appreciated by reference to Figs. 4 and 6 of the drawings. As
shown in Fig. 4, the draft of the vessel V with the chambers 36, 38,
40, 42 and 44 empty of liquid is depicted by the line designated L
in Fig. 4. Because of the low draft of the vessel in its "light
condition" it i5 readily transported to the site of a spill without
interference by the rotatable drums 52 and 54. Upon reaching the
site of an oil spill, the valves 48 for each of the storage chambers
38 and 42 in each of the hulls 10 and 12 are opened, allowing sea
water to enter the storage chambers and to lower the hulls 10 and 12
to a working water line W. In this condition, the storage chambers
38 and 42 in each of the hulls will be filled with sea water to the
level of the water line W.
With the valves 48 opened, the vessel is advanced longi-
tudinally over the area of an oil spill with the drums 52 and 54 ro-
tating in opposite directions as depicted by the arrows R in Fig. 4.As a result of such drum rotation, a mixture of oil and water is
pumped upwardly through the gap between the drums and deposited in
-- 10 --
~063039
the respective distribution trough 88 for discharge to the top of
the four storage chambers 38 and 42. Because the storage chambers
are opened at their bottom and also because the specific gravity of
the oil picked up is less than the sea water, water previously intro-
duced to the storage chambers 38 and 42 will be displaced outwardly
through the valves. Simultaneously the chambers 38 and 42 will oper-
ate in the manner of settling tanks so that water introduced with the
oil through the openings 92 will settle out of the oil ultimately to
be discharged through the open valves 48 as additional oil is intro-
duced to the storage chambers.
The gap between the drums will vary with the conditionsunder which an oil slick is to be recovered. For example, if the
oil slick contains a large amount of relatively heavy debris such as
logs or the like, the gap between the drums will be increased to a
maximum. Other types of debris such as sticks, cans, bottles and
the like will have little effect on the operation of the vessel in-
asmuch as debris of this type will be crushed between the rotating
drums and collected on the screening 94 for removal from the oil and
water mixture passed to the cargo chambers. Because of the independ-
ent drive train for rotating the drums 52 and 54, the speed of rota-
tion may be varied to optimize the recovery operation.
A preferred technique for traversing a relatively small
oil spill is shown in Fig. 6 of the drawings. Here the recovery ves-
sel V is towed by a pair of tug boats T connected to one end of the
recovery vessel by floating booms B. By advancing the recovery ves-
sel slowly against wind and current, it is possible that the entire
oil slick be recovered in one pass of the vessel.
Alternatively, and particularly where larger oil spills
are incurred, it may be desirable to circumscribe the oil spill first
with a circular or closed boom to assure its containment with a de-
fined area. The recovery vessel is maneuvered into the oil spill
and then traversed back and forth until all of the oil has been re-
- 11 - .
: . , ; :.... . , . ~ :.. . ... ~
1063~39
covered. The vessel of the invention is particularly suited to this
type of operation inasmuch as it may be reversed without loss of
time for turning operations and without changing the direction of
rotation of the drums inasmuch as they continue to rotate in the
directions of the arrows R irrespective of the direction of longi-
tudinal movement.
Still another use of the vessel particularly where oil
spill has drifted beneath wharves and like structures which are not
accessible b~ the recovery vessel of the invention. In this situa-
tion, the vessel is placed against the pier or wharf under which theoil spill has spread and both of the drums 52 and 54 initially rota-
ted in the same direction to initiate a current of the spill between
the two hulls 10 and 12. As the current becomes established, the
rotation of the drum which is downstream in relation to that current
can be rotated oppositely from the upstream drum to effect a pumping
action similar to that described above with respect to Fig. 4 of
the drawings.
Although the design of the oil spill recovery and storage
vessel of the invention is adaptable to a wide variation in sizes,
the following exemplary dimensions are given to enable a complete
understanding of the operating parameters of the vessel.
Length overall - 40 ft. 0 in.
Beam overall - 26 ft. 0 in.
Depth of hulls 10 and 12 - 10 ft. 0 in.
Width of each hull - 8 ft. 0 in. :
Draft (light) - 2 ft. 3 in.
Draft (working) - 5 ft. 0 in.
Drum diameter - 8 ft. 0 in.
Drum length - 10 ft. 0 in.
Axle height above working water line (W) -
4 ft. 0 in.
Gap size - 0 in. to 6 in.
- 12 -
,'
1063~39
Given a vessel of the above dimensions, the approximate
storage capacity of the four chambers 38 and 42 is approximately 50
short tons of oil having a specific gravity approximating 0.87.
As an example of the rate at which the vessel may recover
an oil slick, if the drum gap in the above vessel is set to produce
a surface film on each drum of approximately one-quarter of an inch
in thickness and the drums rotated at a speed of approximately 30
r.p.m., approximately 315 cubic feet of li~uid will be picked up by
the vessel per minute. While this represents a rate of approximately
10 short tons per minute, it is to be understood that a substantial
percentage of the liquid picked up will be sea water particularly if
complete collection of all oil is to be assured. A conservative es-
timated percentage might be assumed lO~ oil. At this rate, the stor-
age chambers 38 and 40 will be filled in approximately 50 minutes to
one hour. At this rate, a major oil spill of approximately 200 short
tons can be recovered in approximately five to six hours. It i9 cont~
templated that because of its relative simplicity, the recovery ves-
sel of the present invention could be carried aboard large oil tank-
ers as tenders as for use in the event of oil spills even in the open
sea. Smaller versions than the example given could be handled by
life boat davits and lowered onto the sea for spill recovery. With
large size tankers having a capacity of 300,000 short tons or more,
it is possible that a vessel having the exemplary dimensions given
above could be carried and readily handled by equipment available on ~ -
the deck of such tankers. ~-
Thus it will be appreciated that by the present invention - -
there is provided an improved vessel and method for effective recov-
ery and containment of oil spills. It also will be appreciated by
those skilled in the art that various modifications and/or changes
in the di8clo~ed embodiment can be made without departure from the
concept manifested-by the disclosed embodiment. It is expressly in-
tended, therefore, that the foregoing description is illustrative of
- 13 -
1063039
a preferred embodiment only, not limiting, and that the true spirit
and scope of the present invention be determined by reference to the
appended claims.
- 14 -
.' ,'' . ' ', " '' ~ , .
., . . ' I ''~ ` :
