US 3679058 A
An oil absorbing boom to be deployed across the effluent stream from a separator or settling basin on the downstream side of oil transfer operations at a seaport for the purposes of collecting and removing from the water thin films of oil such as those which sometimes escape from oil spill booms surrounding a tanker at a loading dock, and comprising an elongated flat tubular sleeve of polymer netting enclosing within itself a plurality of flat elongated slabs or bats of "picker-lap" fibrous polymer material such as blown polypropylene film arrayed end to end within the tubular sleeve and sufficiently spaced apart to permit accordion folding of the sleeve at fold lines between adjacent bats, with a tension-bearing rope or cable being positioned within the tubular sleeve alongside the successive plurality of absorbent bats to reinforce the structure for carrying its own weight or impact loads placing it in tension between its ends. Alternatively, a continuous, wide, flat sheet of extremely porous hydrophobic foam material such as fully reticulated polyurethane foam, suspended from overlying buoyant flotation material, is formed into a similar elongated boom deployed across a floating oil film or into a continuous endless belt repeatedly cycled through the floating oil. After trapping oil within the porosities or interstices of the boom or belt material, it is squeezed between pinch rolls to force out and recover the trapped oil, and the device is thus capable of successive repeated deployment cycles of oil recovery operation.
Claims available in
Description (OCR text may contain errors)
United States Patent 1 *July 25, 1972 Smith  OIL COLLECTION BOOM  Inventor: Millard F. Smith, PO. Box 295, Saugatuck, Conn. 06882 Notice: The portion of the term of this patent subsequent to Nov. 10, 1987, has been disclaimed.
 Filed: Jan. 27, 1970  Appl. No.: 6,117
Related U.S. Application Data Primary Examiner-Reuben Friedman Assistant ExaminerT. A. Granger Attorney-Robert H. Ware  ABSTRACT An oil absorbing boom to be deployed across the effluent stream from a separator or settling basin on the downstream side of oil transfer operations at a seaport for the purposes of collecting and removing from the water thin films of oil such as those which sometimes escape from oil spill booms surrounding a tanker at a loading dock, and comprising an elongated flat tubular sleeve of polymer netting enclosing within itself a plurality of flat elongated slabs or bats of picker-lap" fibrous polymer material such as blown polypropylene film arrayed end to end within the tubular sleeve and sufficiently spaced apart to permit accordion folding of the sleeve at fold lines between adjacent bats, with a tension-bearing rope or cable being positioned within the tubular sleeve alongside the successive plurality of absorbent bats to reinforce the structure for carrying its own weight or impact loads placing it in tension between its ends. Alternatively, a continuous, wide, flat sheet of extremely porous hydrophobic foam material such as fully reticulated polyurethane foam, suspended from overlying buoyant flotation material, is formed into a similar elongated boom deployed across a floating oil film or into a continuous endless belt repeatedly cycled through the floating oil. After trapping oil within the porosities or interstices of the boom or belt material, it is squeezed between pinch rolls to force out and recover the trapped oil, and the device is thus capable of successive repeated deployment cycles of oil recovery operation.
6 Claims, 8 Drawing Figures on. COLLECTION BOOM RELATED APPLICATION This application is a continuation-in-part of my co-pending patent application Ser. No. 739,231, filed June 24, 1968, now US. Pat. No. 3,539,013.
BACKGROUND OF THE INVENTION The problem of spilled oil in seaports where oil is transferred daily from tankers to shore installations or other waterborne petroleum transport vessels has become increasingly serious in recent years. Pollution of harbor waters has become the subject of new laws and increasingly firm administrative action in many localities. Oil spill booms such as those shown 'in Millard F. Smith US. Pat. No. 3,146,598 generally serve well to contain oil inadvertently spilled from ruptured hose or a leaking fitting during the normal transfer of petroleum to and from waterborne transport vessels. Occasional leakage passed by conventional oil spill booms which may be caused by a local water disturbance, such as a vessel's wake, sometimes permits the escape of small quantities of oil from a spill which is otherwise successfully contained. This escaping oil spreads on the surface of the water in an extremely thin film, making it very difficult to remove. The resulting deposit of oil along shores, beaches and waterside installations creates an important source of liability for the operators of oil refineries, tankers and oil transfer installations, and the need for skimming-type oil film recovery devices has gone long unfilled.
OBJECTS OF THE INVENTION Accordingly a principal object of the invention is to provide an oil recovery boom capable of being conveniently deployed downstream in the path of current-carried oil film slicks to absorb these slicks. A further object of the invention is to provide systems and apparatus cooperating with such oil absorbing booms for the removal of the boom carrying absorbed oil from the surface of the water, and for separating the absorbed oil from the absorbing boom which may then be prepared for re-use, to be re-deployed as required.
Another object of the invention is to provide readilydepolyable elongated booms and belts of lightweight, highly porous material capable of entrapping and removing substantial volumes of oil from an oil slick or floating oil film. A further object is to provide such devices in self-supporting buoyant assemblies for convenient deployment and repeated re-use.
Other and more specific objects will be apparent from the features, elements, combinations and operating procedures disclosed in the following detailed description and shown in the drawings.
THE DRAWINGS FIG. 1 is a schematic plan view of a maritime oil transfer terminal showing a tanker near a dock surrounded by an oil boom with an oil collection boom of the present invention deployed downstream to collect any escaping oil;
FIG. 2 is an enlarged fragmentary elevation view schematically showing pinch roll apparatus on shore positioned to draw in the boom and separate collected oil from it by compressive pinch roll action;
FIG. 3 is a further enlarged fragmentary perspective view, partially cut away, showing an oil collecting boom of the present invention;
FIG. 4 is a comparable fragmentary perspective view showing the preferred steps in the fabrication of an oil collection boom of the present invention;
FIG. 5 is a greatly enlarged cross-sectional elevation view of an oil collection boom fabricated by the process illustrated in FIG. 4;
FIG. 6 is a schematic perspective view of a different embodiment of the invention;
FIG. 7 is a fragmentary schematic perspective view of still another embodiment of the invention; and
FIG. 8 is a fragmentary perspective cross-sectional view of a further modified embodiment of the invention.
COMPRESSIBLE OIL COLLECTION BOOMS The booms of one embodiment of the present invention take advantage of the substantial interstitial volume incorporated in lightweight bats of polymer fibers or blown polymer film of such materials as polypropylene which present enormous fiber surface area on which oil film deposits itself when a passing current of water on which such a bat floats carries a film of oil into contact with the bat. When this occurs, most or all of the oil film is collected upon the fibrous surfaces inside the bat, and very little oil proceeds downstream beyond the structure.
The oil collection booms of this form of the present invention incorporate a plurality of elongated, flat, rectangular bats of such material, which may be for example Avisun polypropylene No. 101 l, a high molecular weight polymer formed into fine randomly oriented fibers in a bat of fiber material referred to as picker-lap, incorporating fibers having a 2.5 denier, 2 inch long in average length. Similar Avisun polypropylene polymers passed through blown film apparatus at extrusion temperatures in the range between 425 and 450 F produce blown film which may be formed into the same type of extremely lightweight compressible fluffy fibrous bats. Since the specific gravity of polypropylene is about 0.90, these bats of material are buoyant and well adapted to serve as floating oil collection structures.
In the booms of this form of the invention, such as the boom 10 illustrated in the FIGURES, a greatly elongated tubular net sleeve 1 l encloses a series of wide, fiat, thin, elongated bats 12 of this expanded polymer material just described, as shown in FIGS. 3, 4 and 5. The net sleeve 11 is preferably formed of similar lightweight polymer fibers which may be heat-sealed in net configuration or which may be woven or knotted like a fisherman's net in the form and spacing desired. The bats 12 are spaced apart longitudinally within the tubular sleeve 11 by a distance of from two or three times their thickness to permit accordion-folding in the manner of the accordion-folded oil spill boom shown in my US. Pat. No. 3,146,598. In the fabrication process illustrated in FIG. 4, a roll 13 of the netting material 11 is unrolled to draw a length of this material over a work station where a bat 12 is laid lengthwise along one-half of the net 11 drawn from the roll 13. Along the inner edge of the bat 12, a tension cable preferably formed of stainless steel wire rope l4 unreeled from a storage reel 16 is also laid longitudinally down the central portion of the net 11 beside the bats 12. The free half of the net 11 is then folded across the upper surface of the bat 12 at fold point Ila shown in FIG. 4, enclosing the cable 14 and overlapping to bring the opposite edges of the net 11 into juxtaposed relation. Net 11 thus forms a tubular sleeve enclosing the bat 12, with a heat-sealed or stitched edge seam joining these two juxtaposed net edges along the boom edge 17 shown in FIGS. 4 and 5, on the opposite edge of the elongated bat 12 from the edge beside which cable 14 is laid. If desired a comparable seam may be stitched or heat-sealed between cable 14 and bat 12 to form a small cable hem or pocket positioning the cable along the aligned edges of all of the bats 12 along the entire length of the boom 10.
The longitudinal spacing of the bats 12 within the tubular sleeve 11 is maintained by the formation of transverse seams between the bats 12. As shown in FIG. 4, these seams are preferably formed at the time the boom is fabricated. As the net 11 passing the fold point 11a is formed into a sleeve by the sewn or heat-sealed seam 17 along the full length of the bat 12, a pair of transverse seams are preferably formed. The first is a rear end seam 18 extending transversely across the tubular sleeve II at a point directly behind the bat l2, brining its upper and lower surfaces into juxtaposition and stitching or heat-sealing them together along the flattened tubular sleeve toward the next bat 12, a frontend seam 19 likewise extends transversely across the flattened sleeve to form the forward edge of a pocket enclosing the next bat 12, as shown in FIG. 4.
The seam l8 and 19 are spaced apart longitudinally by a distance sufficient to permit the boom to be accordion-folded in a stack such as stack 28 shown in FIG. 2 for storage and shipping. The distance between seams 18 and 19 should preferably be at least equal to the thickness of bats 12 to permit this accordion-folding. Cable 14 may be caught at seams 18 and 19 if desired.
Suitable end fittings such as towing loops or shackles are preferably joined to the extreme ends of the cable 14 by swaged thimble fittings, eye splices or other common wire rope connection techniques.
As shown in FIG. 1, the completed boom is preferably deployed across the major part if not the entire width of a flowing body of water at a point downstream from the transfer terminal at which petroleum products are loaded or unloaded from vessels where spills may occur. Thus in FIG. 1 a tanker 20 is shown in oil transfer position beside a dock 21, surrounded by an oil spill boom 22. Arrows 23 show the direction of the prevailing current passing the installation and the compressible collection boom of the present invention is shown deployed extending partway across the waterway from one shore toward the opposite shore at a point downstream from the tanker 20, positioned to receive oil carried downstream by the current 23.
As shown in FIG. 2, after an oil film has been brought into contact with the collection boom 10 by the prevailing current and after all or the major portion of the oil film carried by the current 23 has been caught and collected in the interstitial spaces between the loosely matted fibers of the bats 12 along the length of the boom 10, the boom may be withdrawn from the waterway by such means as the pinch roll oil separation apparatus illustrated schematically in FIG. 2. In this figure pinch rolls 24 and 26 which may be powered to draw between themselves the compressible boom 10 are shown in power driven operation and the boom 10 is moving from the water between the pinch rolls 24 and 26 which have the effect of compressing each of the bats 12 in turn as these bats are drawn between the pinch rolls. As a result a large portion of the collected oil is squeezed out of the compressible bats 12 into a sump 27 beneath the pinch rolls. The squeezed collection boom 10 issuing from the pinch rolls is preferably accordion-folded in a storage stack 28 near the shore 29 where it is ready for prompt deployment in the event of another oil spill.
Cable 14 provides unusually high strength to the fibrous polymer structure formed by the tubular net sleeve 11 and the lightweight compressible bats 12, serving to position the boom in the shape and configuration and in the direction desired for optimum oil-collecting performance.
In the alternative forms of the invention shown in FIGS. 6, 7 and 8, the oil-collection material is a slab of a different, highlyporous polymer structure known as fully reticulated open-cell foam, preferably formed of polyurethane. This material is formed by exposing open cell polymer foam to heat or chemical action, which has the effect of partially destroying, melting, fusing or vaporizing the polymer cell walls between the open cells, further increasing the porosity and oil collecting capability of this material. This elongated oil-collecting slab may be formed as an endless belt 31 (FIG. 6) or as a greatly elongated boom 32 (FIG. 7).
The hydrophobic character of polyurethane foam, coupled with its light weight and the rather high specific gravity of the urethane cell walls, normally ranging between 1.00 and 1.20, provide unusually effective oil-collecting action. After depbyment on an oil film or slick, the lightweight elongated foam slab 31 or 32 slowly sinks, and its waterline slowly rises through the internal cells as air filling the internal porosities and cells is progressively displaced by the supporting liquid. Floating oil forms the topmost layer of the liquid exposed to all cell walls, progressively forming an overlying layer or coating thereon as the foam slab sinks, while water does not adhere to the hydrophobic urethane surfaces.
As the slab 31 or 32 reaches substantially total immersion, small pockets of air remaining entrapped in blind ends of a few passageways in the foam structure often provide sufficient slight buoyancy, supplementing that of the collected oil, to prevent further sinking or complete submergence of the slabs 31 or 32.
When the slab is withdrawn from the spill or film-covered reservoir or anchorage, water drains freely from the interstices of the foam structure, while the oil remains as a deposited layer or coating on the interstitial cell walls.
Fully-reticulated open cell polyurethane foam may be fabricated in an elongated slab 2 inches thick, twelve inches wide and up to 60 feet long, for example. The belt 31 of FIG. 6 or the elongated boom 32 of FIG. 7 may be formed of one or more of such slabs. When several slabs are joined endwise to form a longer assembly, they may have their ends bonded together by cementing, heating or vibratory bonding techniques.
The belt 31 shown in FIG. 6 is formed as an elongated, continuous slab of such fully reticulated open cell polyurethane foam material, one end of which is immersed in the body of fluid 33 on which a layer of floating oil 34 resides. The opposite end of the belt 31 is interposed between a pair of pinch rolls 36 and 37 cooperating with sump 38 for power driven squeezing of the compressible foam slab belt 31, operating in the same manner as the pinch roll assembly 24-26 of FIG. 2 to recover and collect the oil carried from the slick by belt 31.
In this embodiment illustrated in FIG. 6 however, an elongated, continuous foam slab belt 31 is continuously returned from the pinch roll assembly 36-37 back into the fluid reservoir 33 for continuous recycling immersion, withdrawal and pinch roll oil squeezing recovery operations.
A two-part boom assembly 32 is illustrated in FIG. 7, comprising an oil collection slab 39 having removably mounted thereon an overlying buoyant slab 41 of such buoyant flotation material as closed cell polyethylene foam, for example. Cooperating strips or patches of Velcro material 45 ccmented to the facing surfaces of the two foam slabs 39 and 41 may be employed to secure these slabs in detachable facing relation, providing the two-part assembly shown in FIG. 7.
In the lower righthand corner of FIG. 7, the oil collection slab 39 is shown immersed in the fluid reservoir while the attached buoyant slab 41 floats on the surface of the reservoir. The assembly 32 is shown being drawn toward a pair of pinch rolls 42 and 43 above a sump 44, and as the assembly 32 approaches these pinch rolls the overlying buoyant slab layer 41 is peeled from the upper surface of the oil collection slab 39 and diverted to by-pass the pinch rolls as indicated in FIG. 7.
The oil collection slab 39 passes between the pinch rolls 42 and 43 for compressible squeezing to force out and remove collected oil, which drains from the pinch roll assembly 42- 43 into sump 44. The two slabs 39 and 41 are then directed to be rejoined in facing relationship, and they are directed through a second pair of re-mounting pinch rolls 46 and 47 providing sufiicient compression force to squeeze slab 41 and slab 39 together into close juxtaposition, rejoining their respective Velcro strips or patches 45 and thus remounting the buoyant slab 41 overlying the oil collection slab 39 to reassemble the oil collection boom 32 ready for redeployment. When it is redeployed, the oil collection slab 39 must be suspended beneath buoyant slab 41 on the water-engaging underside of the assembly 32 for reimmersion, again descending through the oil slick to perform the oil collection operation described above. For this purpose, a half twist is customarily given to the rejoined assembly 32, as shown in the upper portion of FIG. 7, and suitable guide rolls may be employed for this purpose if desired.
Other buoyant flotation units may be formed on the compressible slab 39 if desired. For example, as shown in FIG. 8, solid blocks 48 of highly resilient compressible buoyant foam, such as polyethylene foam, may be cemented as abutting strips along the edges of an oil collection slab 39 which is formed of such material as fully-reticulated open cell polyurethane foam, thus producing a unitary foam slab assembly 49 which may be directed between the pinch rolls 42-43 in order to express the oil collected in the central open cell oil collecting foam portion 39. This unitary assembly 49 avoids the need for the separation and recombination of two individual layers like those forming the assembly 32. in the unitary assembly shown in FIG. 8, the width and thickness of the buoyant flotation foam strips 48 are selected to suspend the collection slab 39 at the desired immersion depth, with due regard to the anticipated immersion period and the selection between the belt or the elongated boom configurations illustrated in FIG. 6 and FIG. 7 as alternative forms of the fabricated structure to be employed.
The recycled belt 31 of FIG. 6 is customarily immersed for only a brief period during each cycle, and buoyant suspension of the oil collection slab material is less necessary in this belt 31 embodiment than it is in the elongated boom illustrated in FIGS. 1 4 5 and 7, which may remain exposed to the elements, deployed upon the surface of the slick coated reservoir, for a considerable period of time between oil recovery squeezing pinch r'oll operations. For maximum effectiveness, the elongated booms are customarily buoyantly positioned and maintained by their flotation material at a final equilibrium level closely coinciding with the oil slick surface, in order to achieve maximum interstitial cell wall exposure to floating oil over the entire vertical height of slab 39 during the gradual settling immersion of the boom assembly.
Since the foregoing description and drawings are merely illustrative, the scope of the invention has been broadly stated herein and it should be liberally interpreted to secure the benefit of all equivalents to which the invention is fairly entitled.
What is claimed is:
l. A resilient depressible oil collection boom for collection and removal of oil from the surface of a fluid reservoir comprising:
A. a plurality of thin, flat, elongated bats of highly porous and resiliently depressible material having intercommunicating interstices extending therethrough,
B. associated deployment means including an elongated tubular net sleeve positioning the bats juxtaposed with the surface of the fluid reservoir, with said bats being arrayed inside the length of the sleeve,
C. oil recovery expressing means operatively associated with the sleeve and positioned to depress successive portions of the bats, expelling accumulated oil from the interstices of the depressed portions of the bats,
D. spacing means maintaining the adjacent bats longitudinally spaced apart by distances at least double their thickness, to permit accordion-folding of the boom,
E. a tension-bearing cable extending longitudinally beside said bats along the length of said sleeve, and
F. terminal fittings secured to the ends of the cable near the corresponding ends of the tubular sleeve.
2. The boom defined in claim 1, wherein the net sleeve is formed of polymer fibers.
3. The boom defined in claim 1, wherein each elongated bat is formed of a randomly oriented mass of polymer fibers.
4. The boom defined in claim 1, wherein each elongated bat is formed of a mass of blown polymer film material.
5. The boom defined in claim 1, wherein said spacing means include transverse seams flattening the tubular net sleeve between adjacent bats.
6. The boom defined in claim 1, wherein the cable is formed as a length of stainless steel wire rope.