CA1063039A - Oil spill recovery vessel and method - Google Patents

Abstract

Abstract of the Disclosure A catamaran-type vessel having a pair of transversely spaced longitudinal hulls each being symmetrical longitudinally about a transverse medial line to operate with equal efficiency in fore and aft directions and supporting between the hulls a pair of counter-rotating drums by which an oil slick may be lifted and transferred to cargo chambers on the interior of each of the hulls.
The cargo chambers are symmetrically alternated with hull buoyancy tanks and are equipped with bottom valves by which the draft of the vessel may be lowered to contact the lower periphery of the drums with the surface of an oil slick. Storage of recovered oil in the cargo tanks is effected by flotation of the lighter oil on the ballast water in the chambers and ultimate displacement of the ballast water by the collected oil.

Description

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 -.. ~ .

-,.-. - .. - - - . - ... ~.. , ".... .. ... ..

- : . ,: . : :.
. . . , . . . , . ~ .. . .

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.

,, ,., . , ... .. . : - .~ , :
:. : . . . . . ; - .
- , ~ . , : ,: . , -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 ~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-- ~ :
', : '' . ' ': , ': '~
.

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 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 ~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.

,' 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 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.

.' ,'' . ' ', " '' ~ , .
., . . ' I ''~ ` :

Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An oil spill recovery vessel comprising:
a pair of transversely spaced longitudinal hulls each having a plurality of discrete internal chambers to establish buoyancy tanks and storage chambers;
means for opening the bottoms of said storage chambers to allow ingress and egress of liquid to and from said storage chambers; and means for picking up a mixture of oil and water between said hulls and for introducing said mixture to the top of said storage chambers thereby to effect in said chambers a layer of oil superimposed above water until a sufficient quantity of oil has been introduced into said chambers to displace the water through the bottoms of said chambers, said last mentioned means including a pair of transversely extending, counter-rotatable cylindrical drums spaced longitudinally to establish a gap between the peripheries thereof, both said drums being movable from an elevated inoperative position when said 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 said hulls are floated when the bottoms of said storage chambers are open, the space between said hulls being unobstructed except for said drums at and below said surface of water.

2. The apparatus recited in claim 1 wherein said buoyancy tanks and storage chambers are symmetrically alternated in said hulls.

3. The apparatus recited in claim 1 including scraper means for removing oil and water from the surface of said drums.

4. The apparatus recited in claim 1 including means to adjust the longitudinal position of at least one of said drums thereby to adjust the width of the gap between the drum peripheries.

5. The apparatus recited in claim 1 including indep-endently controlled and separate torque developing means for rot-ating each drum.

6. The apparatus recited in claim 5 wherein said tor-que developing means comprises an independent internal combustion engine for driving each drum.

7. An oil spill recovery vessel comprising:
a pair of transversely spaced longitudinal hulls each having a plurality of discrete internal chambers to establish buoyancy tanks and storage chambers;
means for opening the bottoms of said storage chambers to allow ingress and egress of liquid to and from said storage chambers;
a pair of cylindrical drums of essentially the same diameter supported for rotation on longitudinally spaced trans-verse axes between said hulls, the longitudinal spacing of said axes being equal at least to the combined radii of said drums to provide a gap at the periphery of said drums, said drums being movable with said hulls from an elevated inoperative position when said storage chambers are empty of liquid to a lowered operative position to be in contact with the surface of water in which said hulls are floated when the bottoms of said storage chambers are open, the space between said hulls be unobstructed except for said drums at and below said surface of water;
means for rotating said drums in opposite directions and to effect upward peripheral movement thereof at said gap;
means to remove liquid carried upwardly through said gap from the periphery of each of said drums; and means to transfer said removed liquid to the top of said storage chambers.

8. The apparatus recited in claim 7 wherein said hulls are longitudinally symmetrical about a transverse medial line thereby to enable longitudinal advance of said hulls in fore and aft directions with equal efficiency.

9. The apparatus recited in claim 7 wherein said buoy-ancy tanks and storage chambers are symmetrically alternated longi-tudinally of said hulls.

10. The apparatus recited in claim 7 including means to adjust the longitudinal position of at least one of said drums thereby to adjust the width of the gap between the peripheries of said drum.

11. The apparatus recited in claim 7 wherein the lower peripheries of said drums are elevated above the bottoms of said hulls so that when the bottoms of said storage chambers are opened to allow the ingress of sea water, the draft of said vessel is increased to the level of the lower peripheries of said drums.

12. The apparatus recited in claim 7 wherein said means to remove liquid carried upwardly through said gap comprises an inclined scraper blade extending the full length of each of said drums, said scraper blades being located to engage said drums at approximately 120° of drum rotation from said peripheral gap.

13. The apparatus recited in claim 12 wherein said means to transfer said removed liquid to the top of said storage chambers comprises a trough merging with each of said scraper blades, said trough being screened to prevent the entrance of debris thereinto.

14. The apparatus recited in claim 7 comprising indep-endent internal combustion engines for developing torque to rotate said drums respectively, one such engine being supported on each of said hulls.

15. The apparatus recited in claim 14 including a hydraulic transmission system for transmitting torque from said internal combustion engines to said drums, each of said hydraulic systems including a hydraulic pump driven by the internal combustion engine, a hydraulic motor supplied by said pump and attached to each of said drums and separate hydraulic system control components for each of said drums.

16. The apparatus recited in claim 15 including a control bridge extending between said hulls and elevated above said drums, said control components being located on said control bridge.