BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is related in general to systems for clean-up and recovery of oil spills. In particular, the invention pertains to a system based on the use of an elastomeric oleophilic/hydrophobic foam material suitable for continuous on-site oil extraction and separation.
2. Description of the Related Art
Since the early times of off-shore drilling, concerns over oil spills have created much debate and tension between environmental and production interests. The potential economic damaged resulting from large spills has spurred much research, but no solution has proven to be satisfactorily effective in protecting wildlife and shore lines from major spills. As evidenced by the Exxon Valdez tanker rupture and the recent well blow-out in the Gulf of Mexico, serious periodic accidents are almost unavoidable and the consequences can be disastrous.
Typically, oil spills are addressed first by containment efforts and then by some method of oil collection and remediation. Absorbent floating booms, in-situ bio-remediation, dispersing detergents and controlled fires are all examples of various approaches used to date to control the damage of oil spills. No mobile, continuous process exists for containing an oil spill and at the same time extracting and recovering the oil from the water. The present invention addresses this problem with an effective and highly efficient solution.
BRIEF SUMMARY OF THE INVENTION
The invention is based on the use of an elastomeric foam that has been functionalized to exhibit both oleophilic and hydrophobic properties. Because of its foam structure, this material can be used to entrap oil that can then be pressed out and recovered on account of the material's elastomeric characteristic. The separation of oil from water is enhanced by the hydrophobic property of the foam, while the absorption of oil is greatly enhanced by its concurrent oleophilic characteristics.
The foam material is contained in permeable pods connected to each other in a chain to form a long boom strung in a closed loop around the oil spill, or a portion thereof, for containment and processing. As each pod is brought into contact with the spilled oil, the foam material in the pod absorbs it to saturation, thereby extracting it and separating it from the surrounding water. According to one aspect of the invention, the pods are connected to one another through linked sections of an inflated flexible hose that ensures their buoyancy as well as that of the entire boom. Therefore, the pods and the linking hose components provide a barrier at the surface that contains the spill within the closed loop.
According to another aspect of the invention, the chain of pods is continuously processed in one or more barges that include equipment to press the absorbed oil out of each pod and a conveyor system for retrieving the pods from the water, pulling them through the press, and returning them to the water in a continuous cycle of operation. Positioning buoys with vertical rollers around which the chain of pods can travel are used to retain the general shape of the containment loop defined by the continuous boom.
Several schemes of containment and recovery are considered, some with stationary barges and some subject to tug-boat traction. The latter schemes provide the additional advantage of accumulating the floating oil at the trailing end of the loop where it is continuously recovered at higher density by the moving chain of pods as the processing barge, pulled by the tug boat, proceeds through the water.
Various other purposes and advantages of the invention will become clear from its description in the specification that follows and from the novel features particularly pointed out in the appended claims. Therefore, the invention consists of the features hereinafter illustrated in the drawings, fully described in the detailed description of the preferred embodiments and particularly pointed out in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of a pod made of flexible netting material for housing the elastomeric oleophilic/hydrophobic foam used to practice the invention.
FIG. 2 is another illustration of the pod of FIG. 1 showing the foam material contained in it and the tubing sections supporting and linking the pods in a chain to form a floating boom.
FIG. 3 is an illustrative, schematic, plan view of the type of containment boom achieved by connecting the pods of the invention in a continuous chain with a supporting floating hose of the type shown in FIG. 2.
FIG. 4 illustrates the connection of the pods of the invention though an inflatable hose or tube to form a chain-like boom for containing an oil spill and for recovering the oil it in a continuous cycle of absorption by contact in the water, mechanical separation on a barge, and return to the water for renewed absorption.
FIG. 5 illustrates schematically an intake ramp for conveying the boom to the top of a barge for processing according to the invention.
FIG. 6 illustrates schematically a pressing facility for the mechanical separation of recovered oil from the pods of the invention in a continuous cycle of operation.
FIG. 7 is a top plan view of a buoy suitable for positioning the boom of the invention in a loop encircling an oil spill being reclaimed according to the invention.
FIG. 8 is a schematic cut-out side elevational view of the buoy of FIG. 7.
FIG. 9 illustrates a system where two very long booms are circulated from a barge pulled by a single tug boat and attached to a collection barge to which the recovered oil is pumped for larger scale storage.
FIG. 10 is an illustrative, schematic, plan view of another configuration of containment booms operating as continuous chains from a single reclamation barge connected to a trailing collection barge and pulled by two tug boats.
FIG. 11 is an illustrative, schematic, plan view of a configuration of containment booms operating as continuous chains from two reclamation barges sharing one of the booms, where each barge is pulled by a tug boat.
FIG. 12 is an illustrative, schematic, plan view of a large scale configuration of containment booms operating as continuous chains from four reclamation barges sharing one of the booms.
FIG. 13 is an illustrative, schematic, plan view of an even larger scale configuration of containment booms operating as continuous chains from a multitude of reclamation barges in conjunction with a stationary containment barrier protecting a shore line.
FIG. 14 is a side elevational view of a processing operation on a reclamation barge where three presses operating in sequence are used to progressively remove first water and then recovered oil from the foam material contained in the pods of the invention.
FIG. 15 is a top plan view of the presses of FIG. 14.
FIG. 16 is a cross-section of a pod fitted with longitudinal fins to produce rotation of the pod as it travels through a body of water.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
The invention relies on the use of a foam material that exhibits concurrent oleophilic and hydrophobic properties that allows it to absorb oil while repelling water, a critical condition for the high efficiency of the process of the invention. In addition, the material is both elastomeric and structured as a foam, the combination of which enables the absorption of relatively high volumes of oil per volume of foam (due to the typically large proportion of voids in the foam) and the subsequent mechanical recovery of the oil from the foam simply by squeezing it out of the foam. These properties together make it possible to carry out the process of the invention with speed and efficiency.
The surface functionalization of materials to render them oleophilic by the deposition of appropriate moieties (such as alkyl acrylates, methacrylate, and vinyl compounds of polyesters, polyurethanes, polyepoxides, bisphenol A resins, and phenoxy resins, for example) is commonly practiced in the art of surface functionalization. The hydrophobicity of materials by the addition of non-polar hydrophobic moieties (such as silicone and fluorocarbons) is similarly well understood. See, for instance, Hao Yang, Pihui Pi, Zhi-Qi Cai, Xiufang Wen, Xibo Wang, Jiang Cheng and Zhuo-ru Yang, “Facile preparation of super-hydrophobic and super-oleophilic silica film on stainless steel mesh via sol-gel process,” Applied Surface Science Volume 256, Issue 13, 15 Apr. 2010, Pages 4095-4102. One elastomeric foam exhibiting such combination of oleophilicity and hydrophobicity is the foam currently sold by Tri-State Biopolymers, LLC, of Lake Forest, Calif., under the trademark VOFOAM™.
The term “absorption” is commonly intended to mean a process of diffusion of a substance into another without chemical or physical bonding, while the term “adsorption” is commonly intended to mean the adhesion of a chemical species onto the surface of particles without covalent bonding but through the action of physical attractive phenomena, such as van der Waals forces. Inasmuch as the oleophilicity exhibited by the foam of the invention is a combination of both, these terms are used interchangeably herein for simplicity unless the distinction is relevant to the description. The terms “elastomer” and “elastomeric” refer to polymers with the property of viscoelasticity (colloquially “elasticity”), generally having notably low Young's modulus and high yield strain compared with other materials.
Referring to the drawings, wherein like parts are labeled with like numerals or symbols, FIG. 1 is a schematic diagram of a pod 10 suitable for practicing the invention. The pod 10 is preferably an elongated, substantially cylindrical container made of permeable flexible material, preferably netting 12, through which oil can penetrate rapidly and without obstruction. As shown in FIG. 2, the pod 10 is filled with chunks 14, preferably spherical in shape for volumetric efficiency, of elastomeric foam having substantial oleophilic and hydrophobic properties, as described above.
As illustrated in FIG. 3, many pods 10 are connected together in a long chain to form a floating boom 16 that is placed around an oil spill 18 in a water body (or a portion thereof) in order to contain the oil and prevent its dispersion over a larger area of the body of water. In the preferred embodiment of the invention, each pod 10 is attached to a section 20 of flexible hose or tube threaded though the pod, as shown in the figures (see FIG. 2), and the various hose segments are connected to one another through air-tight quick-disconnect couplers 22, so that a long boom of regularly spaced pods can easily and rapidly be constructed. As shown in FIG. 4, each coupler 22 is equipped with a check valve 24 to inflate the long hose produced by the coupled sections 20 so as to provide the necessary buoyancy for maximum efficiency of the boom 16 in containing and recovering the oil. A zipper 26 or other similar containment means or enclosure may be used to enclose and provide access to the interior of each pod 10.
According to the invention, a closed-loop chain of pods so constructed is used both as a containment boom and as a conveyor for continuously absorbing and releasing the oil contained by the boom. A barge with a press for squeezing the oil out of the pods is provided on site and the pods are continuously fed through the press and released back into the water, thereby creating a continuous cycle of operation. Referring back to FIG. 3, two booms 16 and 16′ are shown operating in parallel with a single processing barge 30, each advancing in the direction indicated by respective arrows A and A′. To effect such movement of the booms, the barge 30 is equipped with respective intake ramps 32, illustrated schematically in FIG. 5 (also showing the front of the barge in elevational view), where a belt conveyor 34 engages the couplers 22 between the pods of the boom and pulls each pod up onto the barge. The upper end of the intake ramp 32 is pivotally mounted on the back side 36 of the barge 30 and is supported at the lower end by a floating structure 38 that includes floating rollers 40 that funnel the pods 10 toward the conveyor 34 for engagement by the belt. A shock absorbing cylinder 40 is used to reduce the effect of water elevation changes produced by waves or turbulence. Power cleats (not shown) and a V-grooved belt can be used in the conveyor 32 to grab each coupler 22 between pods to advance the booms 16,16′ through the barge 30 for processing of the pods.
As also shown in FIG. 6, the pods 10 of each boom 16,16′ are further advanced on the barge 30 by a similar conveyor 42 that advances the boom through at least one press 44, where each pod 10 is squeezed to mechanically remove the oil from the foam 14. Such a press 44 includes a piston 46 that is operated to push downward as each pod is moved through the press by the conveyor 42. A top belt 48, moving on rollers in the same direction and at the same speed of the conveyor 42, is provided under the surface of the piston 46 and is adapted to squeeze the pods without stopping the conveyor and without producing damaging deformation to their structure other than vertical compression and related mechanical extraction of the oil from the foam 14. The motions of the conveyor 42, belt 48 and press 44 are synchronized to ensure as smooth as possible a passage of the pods through the press. The oil released by the process is collected in a storage reservoir in the barge (not shown) through a collection chute 50 under the press 44 for later transport to a tanker or other larger storage facility. The processed pods are then returned to the water, in a continuous cycle of operation, through a similar return ramp 52 at the other end or the side of the barge 30 (see FIG. 3). As the booms 16,16′ circulate as illustrated, each pod 10 is again placed in contact with oil in the water, if any, where it is absorbed, the pod is circulated and pulled back onto the barge 30 and pressed out for recovery in a continuous cycle of operation.
In the embodiment of the invention illustrated in FIG. 3, the barge 30 is intended to be pulled by a tug boat 54 during operation of the recovery system. Each of the booms 16,16′ is constrained by a buoy 56 attached to the front of the barge 30 by a cable 58 that defines, in combination with the relative rigidity of the boom, the shape of the front side of the loops formed by the booms 16,16′ in the water. FIGS. 7 and 8 illustrate in schematic top plan and side elevational views the preferred configuration of the buoy 56. Referring to FIG. 7, two pairs of rolling tanks 60 are mounted vertically on a support structure 62 spaced apart a distance adequate for the pods 10 of the booms of the invention to pass through. The normally empty tanks provide buoyancy for the entire structure and serve as vertical rollers to constrain and facilitate passage of the pods as the boom is circulated through the recovery circuit of the invention. As seen in FIG. 8 (with one half of the structure 62 removed), an additional float 64 is provided under the structure 62 for buoyancy and a remotely controlled rudder 66 facilitates the process of positioning the buoy 56 with respect to the barge 30. In addition, each rolling tank 60 is equipped with valves (not shown) that make it possible to fill the tank with water to different degrees to reduce the buoyancy of the assembly and thus lower the buoy (and therefore also the boom) if necessary to improve the recovery of oil under the surface of the water.
Another buoy 56 at the trailing edge of each boom similarly constrains the trailing edge of the boom in the water (see FIG. 3). A retractable cable 68 attached to a structure connecting the two buoys 56 may be used to lengthen or shorten the portion of boom directly behind the barge, thereby changing the shape of the loops formed by the booms in the water. Those skilled in the art will recognize that such shape will vary with the rigidity of the hose 20 supporting the pods, the distance of the trailing buoys 56 from the barge, the length of the cables 58, the position of the rudders 66 in each buoy, and the speed of the entire system provided by the tug boat 54.
Thus, an oil recovery system has been shown where a closed-loop boom of uniformly spaced pods containing elastomeric oleophilic/hydrophobic foam material is circulated continuously around a predetermined surface section of contaminated water to sequentially absorb oil and release it by pressing it out of the foam in a process carried out on a barge, and the pods are then returned to the water in an expanded condition to repeat the cycle of recovery. Controllable buoys are tied to the boom to define its shape and position and, if necessary, to change the exact depth of the boom skimming operation along the surface of the body of water. As illustrated in FIG. 3, more than one containment and recovery loops can be operated at the same time from a single barge. The system may be run with a stationary barge or in motion, where the barge is pulled by a tug boat while the boom or booms circulate around the loop defined by each.
As one may well imagine, many different schemes of operation are possible by utilizing different numbers of pods, booms and barges alone or in combination with other kinds of equipment, primarily tankers to store large quantities of oil recovered from the barges. For example, FIG. 9 illustrates a system where two very long booms 70,70′ (shown open ended large but in fact enclosed to define continuous loops) are circulated from a barge 30 pulled by a tug boat 54 and attached to a collection barge 72 to which the recovered oil is pumped for larger scale storage. The barge 72 may be replaced by an empty one as needed without interruption of operations. A barrier 74 of floating pods or other protective material can be used on each side of the barge 30 to prevent the oil from escaping through the intake and return ramps 32 and 52.
Another scheme of operation is illustrated in FIG. 10, where two tug boats 54 are used to pull a barge 30 operating in the same configuration of FIG. 3 but also towing a collection barge 72. FIG. 11 illustrates a scheme where a larger boom loop 76 is shared between two barges 30 towed concurrently by respective tug boats 54. In both configurations the rest of the equipment is utilized as described.
FIG. 12 illustrates a large scale configuration wherein four barges 30 operate in stationary manner sharing a very large inner boom loop 78 concurrently with respective outer boom loops 80. The figure shows three collection barges 72 attached to respective recovery barges 30 and other service vessels 82 in transit within the area of reclamation. FIG. 13 illustrates a case where a barrier 84 has been placed in front of a coast line L to prevent spilled oil from reaching it while the recovery system of the invention is operating in various configurations on the other side of the barrier 84.
While the invention may be practiced effectively as described, it has been demonstrated that a more efficient recovery approach requires that the oil be recovered from the pods 10 in two, preferably three press stages. As shown in elevational and top views in FIGS. 14 and 15, respectively, an optimal way of separating the oil from the foam 12 in the pods 10 of the invention is to first compress the pods to about 90 percent of their saturated volume in a first press 86. This first step remove essentially all water that necessarily remains entrapped by the pods in spite of the foam's hydrophobicity. This oily water is preferably treated on the barge, such as in hydrocyclones or centrifuges (not shown), to recover the oil and return the water off the barge. The pods 10 are then pressed to full compression in a second press unit 88, where essentially water-free oil is completely squeezed out of the pod. If a more gradual compression of the pods is desired without affecting the overall speed of oil recovery, a third press 90 may be added to the operation, each extracting a fraction of the oil carried by the pods.
Because the bottom part of each pod 10 is exposed more directly to oil than the top part of the pod, the oil is absorbed more rapidly at the bottom and the top portion tends to become saturated more slowly by diffusion and oleophilic attraction. Therefore, depending on conditions, the pods may not be completely saturated prior to being conveyed to the barge for the recovery the oil. In order to ameliorate this condition, as illustrated in cross-section in FIG. 16, an embodiment of a pod 10 of the invention may include longitudinal fins 92 that cause the pod to rotate as it is being dragged through water, thereby improving the exposure of all parts of the pod to the oil on the surface of the water.
While the invention has been shown and described herein in what is believed to be the most practical and preferred embodiments, it is recognized that departures can be made therefrom within the scope of the invention. For example, optimization studies currently in effect have shows that the removal of oil from the pods may be improved by having the two conveyors 42 and 48 operating in the presses 44, 86, 88 and 90 (or in selected ones of them) disposed at a converging angle, rather than in the parallel position shown in FIG. 6.
It is also understood that a single large pod could be used in combination with a processing vessel to recover oil from a relatively small area affected by an oil spill. Such a pod could be exposed to the oil and processed through a continuously moving boom, as described, or in batch fashion, by dipping it in the oil spill and retrieving it for processing as needed. Therefore, the invention is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent processes and products.
Patent Application
20120009017
