Abstract:
An apparatus and method for skimming oil and other liquid hydrocarbons and contaminates floating at the surface of a body of water or other suspending liquid. A rigid skimming surface such as a drum or disc is floatably supported on pontoons. The skimming surface is rotatable about an axis substantially parallel to the water surface. The skimming surface is covered with removably attached sorbent material which improves the efficiency of the oil recovery operation and which, when worn or soggy, can be removed and discarded without discarding the skimming surface.

Description:
REFERENCE TO PRIOR APPLICATION 
     This application claims the benefit and priority of U.S. Provisional Patent Application Ser. No. 61/108,927 filed on Oct. 28, 2008, which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an apparatus and method for recovering and removing oil floating on a body of water by scraping the oil from one or more rigid skimming surfaces such as discs or drums that are continuously rotated into and out of the floating oil. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to skimming devices used to recover and remove oil and other liquid hydrocarbons and contaminates floating at, i.e., on or near, the surface of a suspending liquid such as water, as for example, to recover and remove oil that has been accidentally spilled from a marine vessel or ruptured pipeline situated in or near a body of water. Typically, due to the relative density of most oils and other liquid hydrocarbons as compared to water, the liquid hydrocarbons will be located at the water surface. More particularly, the present invention relates to skimming devices having rigid skimming surfaces such as discs and drums, wherein the discs and drums are covered with removably attached sorbent material and wherein said sorbent material (a) improves the efficiency of the recovery operation, and (b) can be easily removed and replaced. 
     One of the advantages of the invention disclosed herein resides in the fact that the sorbent material covering is removably attached to the discs and drums, thereby facilitating removal of said sorbent material in the event that the operator needs or wants to replace used sorbent material with fresh sorbent material, as for example if the material becomes worn, soggy, or otherwise unable to continue to efficiently sorb oil. This advantage is absent from the prior art. 
     Moreover, environmental regulations generally require that oil recovery equipment must be free of all contaminants prior to being released from the oil recovery site. Compliance with such regulations is comparatively easy and inexpensive for the present invention, as the contaminated material covering the discs and drums can be quickly and easily removed from the discs and drums, allowing such contaminated material to be bagged and discarded. By way of contrast, the only way to clean contaminants from discs in the prior art is to either throw away the discs themselves, or to wash them in place at the recovery site. The former alternative is prohibitively expensive. The latter alternative would require so much time and effort, and generate so much contaminated wash water which in turn would have to be treated, as to render the prior art impractical. 
     BRIEF SUMMARY OF INVENTION 
     The present invention provides a rigid-surface oil skimmer, such as a disc skimmer and a drum skimmer, with removably attached sorbent material covering the rigid skimming surfaces, said sorbent material dramatically improving the efficiency of the oil recovery operation. If the sorbent material becomes soggy, worn out or otherwise unable to continue to efficiently sorb oil, or when the oil recovery operation has been completed, the sorbent material can be quickly and easily removed from the rigid skimming surfaces, thereby avoiding the need for more costly and impractical alternatives like discarding or cleaning the rigid skimming surfaces at the recovery site. 
     For disc skimmers, the sorbent material covering is preferably shaped in the form of semi-circular or fully circular pockets which accommodate and sandwich each disc. For drum skimmers, the sorbent material covering preferably has a rectangular shape and is wound around the cylindrical surface of the drum. Overlapped and overlapping flaps of the sorbent material coverings are configured in a way to prevent the scraper from unintentionally pulling them apart, and said flaps are fastened together in a manner which can be quickly and easily unfastened for removal of the material coverings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a side elevational view of the present invention as embodied in connection with a disc skimmer having two rows of discs. 
         FIG. 2  is a top view taken along lines  2 - 2  in  FIG. 1 . 
         FIG. 3  is a side elevational view of a disc used in connection with the invention depicted in  FIG. 1 . 
         FIG. 4  is a side elevational view of a semi-circular shaped pocket of oil sorbent material used to cover the disc depicted in  FIG. 3 . 
         FIG. 5  is an end view taken along lines  5 - 5  of  FIG. 4 . 
         FIG. 6  is a side elevational view showing two of the pockets depicted in  FIG. 4 , located above and below the disc depicted in  FIG. 3 , indicating how the pockets are to be slid together so as to sandwich and cover the disc inside the pockets. 
         FIG. 7  is a side elevational view showing the disc depicted in  FIG. 6  after it has been sandwiched inside and completely covered by the two pockets depicted in  FIG. 6 . 
         FIG. 8  is a fragmentary, cross-sectional view taken along lines  8 - 8  of  FIG. 7 , showing the orientation of the overlapping and overlapped flaps located on the left side of the pockets depicted in  FIG. 7 . 
         FIG. 9  is a fragmentary, cross-sectional view taken along lines  9 - 9  of  FIG. 7 , showing the orientation of the overlapping and overlapped flaps located on the right side of the pockets depicted in  FIG. 7 . 
         FIG. 10  is a fragmentary, perspective view depicting part of the row of clockwise-rotating discs appearing in  FIG. 1 . 
         FIG. 11  is a perspective view of the present invention as embodied in connection with a drum skimmer. 
         FIG. 12  is a perspective view of the drum skimmer depicted in  FIG. 11 , showing the placement and orientation of overlapping and overlapped flaps of the sheet of sorbent material covering the surface of the drum. 
         FIG. 13  is a cross sectional view taken along lines  13 - 13  of  FIG. 11 . 
         FIG. 14  is a side elevational view showing a disc and an alternative embodiment of a disc covering comprised of sorbent material shaped in the form of a fully circular pocket having an opening defined by two flaps, indicating how the disc is to be slid inside and covered by the pocket. 
         FIG. 15  is a side elevational view showing the disc depicted in  FIG. 14  after it has been sandwiched inside and completely covered by the alternative pocket depicted in  FIG. 14 . 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  generally depict the device of the present invention as preferably embodied in connection with a disc skimmer  10 . Skimmer  10  is preferably equipped with a float such as pontoons  12 , which allow the device to floatably rest on the surface  14  of the body of water or other suspending liquid from which the oil or other liquid hydrocarbons or contaminate is to be removed. The pontoons may be provided with a sloped forward portion  13  to facilitate towing of the skimmer in the forward direction. 
     In the preferred embodiment, a plurality of discs  16  are supported by the pontoons  12 . Discs  16  are rotatable about an axis  18  which in the preferred embodiment is substantially parallel to the water surface  14 . The axis of rotation  18  for discs  16  is preferably positioned relative to pontoons  12 , sufficiently near the water surface  14 , such that when the device is floating on the water, a portion of each disc  16  is below and a portion of each disc  16  is above the water surface  14  as best depicted in  FIG. 1 . 
     Discs  16  are preferably thin, circular-shaped plates, as shown in  FIGS. 3 and 10 . Discs  16  can be comprised of any rigid material, preferably metal, such that the discs maintain their shape and orientation when in use. Discs  16  are preferably axially mounted on a rotating shaft  20 , as depicted in  FIGS. 2 and 10 . Each disc  16  preferably has a center opening  22  which is shaped to correspond with the cross-sectional shape of shaft  20 , as for example the square shape shown in  FIGS. 3 and 10 . 
     Discs  16  are covered, either partially or fully, with a sorbent material  24 , preferably the “Fuzzy” type oil-sorbent material offered by Abanaki Corporation of Chagrin Falls, Ohio. As best shown in  FIGS. 4 ,  5 ,  8  and  9 , the sorbent material  24  preferably has a great multitude of short, hair-like fibers  26  no more than about 0.25 inches in length, extending like a dense coat of short fur from a flexible skin  28 . Skin  28  is preferably made of a durable material such as polypropylene or polyethylene. The fibers  26  of sorbent material  24  may have a “nap” such that when fibers  26  are rubbed in the direction of the nap, they tend to lay down, and when fibers  26  are rubbed against the direction of the nap, they tend to stand up. In the preferred embodiment of disc skimmer  10 , each disc  16  is substantially covered with sorbent material  24 , as best shown in  FIGS. 7 and 10 . Sorbent material  24  is preferably configured to correspond with the shape of the disc being covered thereby, as for example the circular shape shown in  FIG. 7 . 
     If the sorbent material  24  has a nap, then the material covering each disc is preferably comprised of two semi-circular shaped pockets  30 , as depicted in  FIGS. 4 through 6 . Each pocket  30  is comprised of two semi-circular shaped halves of sorbent material which are initially fastened together along their semi-circumferences, as for example by stitches  32  as shown in  FIG. 4 , with fibers  26  on the outside and skin  28  on the inside of pocket  30 . Accordingly, each pocket  30  contains an opening  34  which allows the pockets to slip over, accommodate and completely sandwich disc  16 , as shown in  FIGS. 6 and 7 . Each pocket  30  is also provided with an opening  44  to accommodate rotating shaft  20  which passes therethrough, as best depicted in  FIGS. 4 ,  6 ,  7  and  10 . 
     The straight edges  36  of pockets  30  preferably over-lap each other when pockets  30  are brought together, creating overlapping flaps  37  and corresponding overlapped flaps  39 , as best shown in  FIGS. 7-9 . To keep pockets  30  in place, sandwiched around disc  16 , the overlapping flaps  37  and the overlapped flaps  39  are fastened together by fastening means which are well known in the trade, e.g., by the use of glue or other fastening means such as Velcro®. 
     In order to prevent disc  16  from rotating separate and independent from its covering of sorbent material  24 , the respective sides  38  of each pocket  30 , as best shown in  FIG. 5 , are preferably sewn together via stitches  40  which pass through disc  16  by way of a plurality of slots  42  in the disc, as depicted in  FIGS. 3 ,  6  and  7 . In addition or as an alternative to the use of stitches  40 , pockets  30  may be maintained in place on disc  16  by the use of other fasteners known in the trade, such as Velcro® or snaps passing through slots  42 , or via the use of double-sided adhesive tape. For example, a strip of double-sided adhesive tape may first be adhered to disc  16 , such that when the disc  16  is then sandwiched inside pocket  30 , the skin side  28  of the pocket can become adhered to the other side of said tape. 
     Disc skimmer  10  may have one or more rows of discs  16 , each row having a plurality of discs  16  axially mounted on respective shafts  20 , as best shown in  FIG. 2 . In the preferred embodiment shown in  FIGS. 1 and 2 , the two rows of discs are rotated in opposite directions as indicated by arrows  45 , the forward row rotating counter-clockwise and the aft row rotating clockwise, as shown in  FIG. 1 . 
     Shaft  20  is preferably rotated via power supplied by a motor, such as hydraulic motor  46  depicted in  FIGS. 2 and 10 . Hydraulic motor  46  is attached to rotating shaft  20  in a way that is well known in the trade, as for example by the combination of sleeve  48 , bearing  50  and nut  52  shown in  FIG. 10 . 
     Scrapers  54 , which are preferably V-shaped as shown in  FIG. 10 , are located above water surface  14  running along the sides of discs  16 , as best shown in  FIGS. 1 ,  2  and  10 . Scrapers  54  are preferably made of a rigid but somewhat pliant material such as hard plastic. The side edges  56  of scrapers  54  are in contact with and bear against discs  16  and their respective coverings of sorbent material  24 . 
     As hydraulic motor  46  rotates shaft  20 , the discs  16  which are axially mounted on said shaft likewise rotate, such that the disc portions which were immersed below water surface  14  are rotated above the water surface, carrying oil which has been sorbed by the material  24  covering the disc portions which were immersed. As the discs continue to rotate, the oil-sorbed portions of material  24  are rotated further and thereby brought into contact with the side edges  56  of scrapers  54 , which scrape the sorbed oil from the material as best shown in  FIG. 10 . 
     In the preferred embodiment, the V-shaped configuration of scrapers  54  facilitates the collection and channeling of scraped oil which falls by the force of gravity from scrapers  54  into a trough assembly which is in fluid communication with scrapers  14 . Said trough assembly is configured to collect and dispose oil, and said assembly includes trough collection members  58 , as best depicted in  FIGS. 1 ,  2  and  10 . Trough collection members  58  are also preferably V-shaped, and said members  58  preferably rest on and are supported by spacers  60 . Spacers  60  preferably have V-shaped surfaces, as best shown in  FIG. 10 , and said spacers  60  are preferably axially mounted on shaft  20 . 
     In the preferred embodiment shown in  FIG. 10 , a scraper mounting support  62  extends from and is in fluid connection with trough collection member  58 . Scrapers  54  can be attached to scraper mounting support  62  by means which are well known in the art, as for example by pop rivets  64  as shown in  FIG. 10 . 
     Trough collection members  58  are inclined downwardly in the direction of sump  66  as shown in  FIGS. 1 and 10 , thereby facilitating the flow of oil via gravity from the trough collection members  58  into sump  66 . As shown in  FIG. 10 , the oil exiting trough collection members  58  falls by gravity into sump  66 . In the preferred embodiment, the trough assembly also includes trough support such as rods  68  depicted in  FIG. 10  which support, reinforce and connect the oil-exiting ends of trough collection members  58 . 
     From sump  66 , the oil can be pumped via pump  70  through discharge conduit  72 , which conveys the recovered oil out of and away from disc skimmer  10  to a remote location for treatment, storage or further handling. A relief valve  74  as depicted in  FIG. 1  may be situated downstream from pump  70  in order to relieve hydraulic pressure in conduit  72  in case the conduit should become clogged or blocked. 
     It will be understood that the oil removal process described above is continuing and ongoing as the discs  16  continue to rotate non-stop. The oil-sorbed portion of material  24  covering each disc  16 , having rotated under and past scrapers  54 , is thereby relieved of most if not substantially all of the oil it was carrying and, as the disc rotation continues, becomes immersed again in the ongoing process as described above. 
     In order to minimize the risk that straight edges  36  of pockets  30 , as shown in  FIGS. 4-9 , may become unfastened or otherwise separated when being rotated under scraper  54 , the overlapping and overlapped flaps of the sorbent material covering a particular disc are preferably configured differently, depending upon whether that disc is used in clockwise or counterclockwise rotation.  FIGS. 7-9  show the preferred configuration of overlapping flaps  37  and overlapped flaps  39  for a clockwise-rotating disc, as for example the discs shown in  FIG. 10 , as well as the aft row of discs shown in  FIG. 1 . 
     Referring to the upper pocket  30  in  FIGS. 7 and 8 , the straight edges  36  of the left side of said upper pocket are used as part of overlapping flap  37 , while the straight edges  36  of the right side of said upper pocket, as shown in  FIGS. 7 and 9 , are used as part of overlapped flaps  39 . By virtue of said configuration, as said disc rotates clockwise as depicted in  FIGS. 7 and 10 , scrapers  54  will have a tendency to push overlapping flap  37  down and keep it in place over the overlapped flap  39 . 
     For discs to be used for counterclockwise rotation, as for example the discs in the forward row shown in  FIG. 1 , the configuration of overlapping and overlapped flaps would preferably be reversed as compared to a clockwise-rotating disc. More specifically, for a counterclockwise-rotating disc, the straight edges of the left side of the upper pocket are preferably used as part of overlapped flaps  39 , while the straight edges  36  of the right side of that same pocket are used as overlapping flaps  37 . 
     If sorbent material  24  has a nap, then such sorbent material covering disc  16  is preferably oriented relative to said disc in the preferred embodiment such that as the disc rotates, the fibers  26  of sorbent material  24  are scraped by scrapers  54  in the general direction of the nap, tending to lay said fibers down as they pass under the scraper. It is believed that it is more advantageous for scrapers  54  to scrape sorbent material  24  in the direction of the nap rather than against the direction of the nap, in order to avoid the risk of excessive wear, tear and loss of fibers  26 . Accordingly, the nap orientation of sorbent material  24  in the top pocket depicted in  FIG. 7  will preferably be opposite of the nap orientation for the bottom pocket shown in  FIG. 7 . Similarly, the nap orientation of the sorbent material  24  covering clockwise-rotating discs will preferably be opposite of the nap orientation of the sorbent material covering counterclockwise-rotating discs. 
     The sorbent material  24  covering disc  16  can be easily removed from the discs by disconnecting or otherwise disabling the fasteners. For example, the sorbent material  24  covering the disc in  FIG. 7  may be removed by using a knife to cut through the overlapping and underlappng flaps when they are glued together, and by cutting through stitches  40 . By way of further example, if Velcro® were used as the fastener keeping the overlapping and overlapped flaps together, the material covering the disc may be removed by simply pulling the Velcro® fasteners apart and cutting through stitches  40 . 
     If nap is not a concern, as for example if sorbent material is used which has little or no nap, then the alternative disc-covering configuration shown in  FIGS. 14 and 15  is preferred, as it is quicker and easier to attach and detach from disc  16  than is the case with the embodiments appearing in  FIGS. 4 through 7 . As shown in the upper drawing of  FIG. 14 , a fully circular pocket  200  is preferably comprised of two circular-shaped pieces of sorbent material  24 , which are fastened together skin-side  201  to skin-side  201  along approximately 180 degrees of their perimeter, as for example by stitches  204 . Accordingly, circular pocket  200  contains flap portions  206  which define an opening  202  of pocket  200  accommodating disc  16  into which the disc is inserted. The remaining perimeter of circular pocket  200  may then be fastened together, thereby completely covering and securing disc  16  inside pocket  200 , as shown in  FIG. 15 . To prevent disc  16  from rotating separate and apart from its fully-circular pocket  200 , the two circular pieces of sorbent material may be fastened together by way of fasteners passing through slots  42 , as for example by stitches  208  as shown in  FIG. 15 . 
       FIGS. 11-13  generally depict the present invention as preferably embodied in connection with a drum skimmer  100 . Drum skimmer  100  is preferably equipped with flotation means, such as pontoons  101 , which allow the device to floatably rest on the surface  14  of the body of water or other suspending liquid from which oil or other liquid hydrocarbons or contaminate is to be removed. Pontoons  101  may be provided with sloped forward portions  103  to facilitate towing of drum skimmer  100  in the forward direction, as for example through the use of tow lines attached via eyelets  102 . Pontoons  101  may also be equipped with handles  105  to facilitate lowering and lifting of the drum skimmer device into and out of the water. 
     In the preferred embodiment depicted in  FIG. 11 , at least one drum  104  is supported by pontoons  101 , said drum being rotatable about an axis  106  which is substantially parallel to the water surface  14 . The axis of rotation  106  for drum  104  is preferably positioned relative to pontoons  101 , sufficiently near the water surface  14 , such that when the device is floating, a portion of drum surface  114  is below and a portion of drum surface  114  is above the water surface as shown in  FIG. 13 . 
     Drum  104  is preferably cylindrically-shaped and preferably hollow with closed ends. Drum  104  is comprised of a rigid material, preferably metal, such that the drum can maintain its shape and orientation when in use. Drum  104  is preferably axially mounted on rotating shaft  108 , as best depicted in  FIGS. 11 and 12 . Shaft  108  is preferably rotated via power supplied by a motor, such as hydraulic motor  110 . In the preferred embodiment shown in  FIG. 11 , hydraulic motor  110  is attached to rotating shaft  108  in a way that is well known in the trade, and may include a gear reducer  112  which allows for control of the rotational speed of drum  104 . 
     The cylindrically-shaped surface  114  of drum  104  is covered, either partially or fully, with sorbent material  116 , preferably the “Fuzzy” type oil-sorbent material offered by Abanaki Corporation of Chagrin Falls, Ohio. Sorbent material  116  preferably has a great multitude of short, hair-like fibers no more than approximately 0.25 inches in length, extending like a dense coat of short fur from a flexible skin  118  as depicted in  FIG. 12 . Skin  118  is preferably made from a durable and flexible material such as polypropylene or polyethylene. The fibers of sorbent material  116  may have a “nap” such that when the fibers are rubbed in the direction of the nap, they tend to lay down, and when the fibers are rubbed against the direction of the nap, they tend to stand up. 
     In the preferred embodiment of drum skimmer  100 , the cylindrically-shaped surface  114  of drum  104  is completely covered with sorbent material  116 , as best shown in  FIG. 11 . The sorbent material  116  is preferably applied to surface  114  of drum  104  in the form of a single, rectangular-shaped sheet of material  116 . Said sheet of material preferably has a width corresponding to the axial length of drum  104 , and said sheet has a length which at least slightly exceeds the circumference of the drum, such that there will be an overlapping flap  120  and overlapped flap  122  of material  116  when the sheet is completely wrapped around drum  104 , as best depicted in  FIG. 12 . 
     To keep the sheet of sorbent material  116  wrapped around drum  104 , the overlapping flap  120  and the overlapped flap  122  are preferably fastened together using well known fastening means, as for example by using Velcro® as shown in  FIG. 12 , or by using other fastening means such as glue. 
     In order to prevent drum  104  from rotating separate and independent from its covering of sorbent material  116 , an adherent such as a strip of double-sided adhesive tape  124 , as shown in  FIG. 12 , can be used. It will be understood that tape  124  is adhesive on both sides, such that one side of the tape adheres to drum surface  114  and the other side of the tape adheres to skin  118  of sorbent material  116 . 
     In the preferred embodiment of drum skimmer  100  shown in  FIG. 12 , the sheet of sorbent material  116  is applied to drum surface  114  as follows: a strip of double-sided adhesive tape  124  is applied so that it adheres to the skin  118  of the sheet running along, underneath, and adjacent to the edge of the sheet that is to be used as overlapped flap  122 . Said overlapped flap  122  is then positioned as desired on drum  104 , skin-side  118  down, so that the other side of tape strip  124  is brought into contact with and adheres to drum surface  114 . It will be understood that the strip of tape  124  or other adherent may be placed first on the drum surface  114 , and that the skin side of the sheet running along, underneath, and adjacent to overlapped flap  122  may then be pressed into place on top of drum surface  114 , thereby becoming adhered to the strip of tape or other adhesive that had been first placed on the drum. 
     After overlapped flap  122  has been secured to drum  104 , the drum is rotated through one revolution, such that the sheet of sorbent material  116  becomes wrapped around and preferably covers the entire cylindrically-shaped surface  114  of the drum. During this process, additional strips of double-sided tape or other adherents may be applied between the skin  118  and the drum surface  114 , thereby further securing the sheet of sorbent material  116  to drum  104 . For example, additional strips of double-sided tape may be applied at every quarter-turn of drum  104  as the sheet of sorbent material  116  is being wrapped around drum  104 . 
     To complete the application of the sorbent sheet of material  116  to drum  104 , overlapping flap  120  and overlapped flap  122  are preferably fastened together, as for example, by use of fastening means such as corresponding strips  125  of Velcro® as shown in  FIG. 12  or by other fastening means such as glue. 
     In the preferred embodiment shown in  FIGS. 11 and 12 , the direction in which the fastened flaps  120  and  122  rotate under and past scraper  126  determines which flap is to be used as overlapped flap  122  and which is to be used as overlapping flap  120 . More specifically, the fastened flaps are configured such that as they rotate under and past scraper  126 , the scraper will have a tendency to push overlapping flap  120  down and keep it in place over the overlapped flap  122 , as shown in  FIGS. 11 and 12 . 
     In the preferred embodiment of drum skimmer  100 , the sorbent material  116  covering drum  104  is oriented relative to the drum such that as the drum rotates, the fibers of sorbent material  116  are scraped by scraper  126  in the general direction of the nap, tending to lay said fibers down as they pass under scraper  126 . 
     The sorbent material  116  covering drum  104  can be easily removed from the drum by disabling or disconnecting the fasteners. Referring to  FIG. 12  for example, the overlapping and overlapped flaps may be disconnected from each other by simply pulling overlapping flap  120  off of the overlapped flap  122 . If said flaps had been fastened together by glue, a knife could be used to cut through the flaps where they were glued together, thereby effecting separation of the flaps. 
     After the overlapping and overlapped flaps have been disconnected, material  116  can be unwound off drum  104  by simply pulling on the material. As the material is pulled and completely wound off drum  104 , said drum will turn through one complete revolution. During that process, the resistance to movement provided by the double-sided tape strip(s) or other adherents may be easily overcome by simply pulling the material  116  with a bit more force, away from the drum at the place(s) where the tape or other adherent was located. 
     Scraper  126  can be connected to drum skimmer  100  by means of mounting bracket  128  as shown in  FIGS. 11 and 12 . Scraper  126  may be attached to bracket  128  in any number of ways which are well known in the trade, for example by pop rivets  130  shown in  FIG. 12 , and mounting bracket  128  can in turn be similarly attached to drum skimmer  100 , as for example by passing fasteners through eyelets  132  in bracket  128 . Scraper  126  is preferably made of a rigid but somewhat pliant material such as hard plastic. The edge  134  of scraper  126  is in contact with and bears against drum  104  and the sorbent material  116  covering the drum surface  114 . 
     As hydraulic motor  110  turns shaft  108 , drum  104  which is axially mounted on said shaft likewise turns, such that the portion of drum  104  which was immersed below water surface  14  is rotated above the water surface, carrying oil which has been sorbed by the material  116  covering the portion of drum surface  114  which had been immersed. As the drum continues to rotate, the oil-sorbed portion of drum-covering material  116  is rotated further and is thereby brought into contact with scraper edge  134 , which scrapes the sorbed oil from the material as best shown in  FIGS. 11 and 13 . As depicted in  FIG. 13 , the scraped oil flows by the force of gravity into a trough assembly which is in fluid communication with scraper  126 . The trough assembly is configured to collect and dispose oil, and said assembly includes trough collection member  136 . Trough collection member  136  may extend between and may be supported by pontoons  101 , as best depicted in  FIGS. 11 and 12 . 
     In the preferred embodiment, trough collection member  136  is in fluid communication with the interior of at least one of the pontoons  101 , as shown in  FIG. 13 , such that the oil can drain via gravity from trough collecting member  136  into said pontoon which serves as a sump for the oil, all as depicted in  FIG. 13 . From there, the oil can be transported from said pontoon via discharge line  138 , with the assistance of a pump, vacuum or similar means, thereby moving the oil out of and away from drum skimmer  100  to a remote location for treatment, storage or further handling. 
     It will be understood that the oil recovery operation described above in connection with drum skimmer  100  is continuous and on-going as drum  104  continues to rotate non-stop. The oil-sorbed portion of material  116  covering drum surface  114 , having rotated under and past drum scraper  126 , is thereby relieved of most if not substantially all of the oil it was carrying and, as the drum rotation continues, becomes immersed again in the ongoing process as described above. 
     It will also be understood that there may be application of the present invention in connection with disc skimmers and other rigid-surface skimmers which are not equipped with or mounted directly on pontoons or other flotation means. For example, the present invention may be employed in connection with an industrial process involving a tank of water or other suspending liquid having a surface elevation with little or no fluctuations. In such application, the device of the present invention would not require pontoons or other floatation means but could instead be affixed to the side of the tank. Alternatively, the device of the present invention could be kept afloat indirectly, i.e., without its own flotation means, as for example by being secured to the hull of a boat or other floating structure. In such applications, the discs, drum or other rigid-surface skimmers of the present invention could be attached to a non-floating structural support, or to an independently floating structure, at a location such that a portion of the skimming surface is above and a portion of the skimming surface is below the water surface. 
     Moreover, it will be understood that as an alternative to scrapers, the sorbed oil could be removed from the sorbent material of the present invention by way of one or more rollers mounted in place of scrapers. The rollers bear against the sorbed material thereby squeezing the sorbed oil from the sorbed material. 
     The present invention has been subjected to rigorous testing conducted on numerous occasions by qualified personnel at the Ohmsett test facility located in New Jersey, which is managed by the United States Minerals Management Service. Those tests were witnessed by representatives of various organizations having an interest in oil spill recovery, including the United States Coast Guard, Tesoro Maritime Company, BP Shipping Limited and ConocoPhillips Company. The tests were conducted in accordance with the most recent (2008) standards of the American Society of Testing and Materials (“ASTM”), specifically the (F2709-08) Standard Test Method for Determining Nameplate Recovery Rate of Stationary Oil Skimmer Systems. The tests measured, among other things, the oil recovery rate (“ORR”) of the present invention in terms of the volume of oil recovered per unit of time (gallons per minute or “gp”). 
     The tests showed that the ORR for a disc skimmer equipped with sorbent material in accordance with the preferred embodiment of the present invention was on average approximately three times higher than the ORR for the same disc skimmer which was not so equipped. For example, in one representative test, the ORR for a disc skimmer equipped in accordance with the present invention was approximately 386 gpm, whereas the ORR for that same disc skimmer which was not so equipped was only 128 gpm. The oil used in conjunction with that test was “fresh” Alaska North Slope (“ANS”) crude oil having the following properties: Density, g/ml@ 77° F.=0.876; and Viscosity, cP@ 82° F.=14. 
     PARTS LIST 
     Part No. Description 
     
         
         
           
               10  disc skimmer 
               12  float (pontoons) of disc skimmer  10   
               13  sloped forward portion of pontoons  12   
               14  water surface 
               16  discs 
               18  axis of disc rotation 
               20  rotating shaft for discs 
               22  center opening of disc  16   
               24  sorbent material covering disc  16   
               26  hair-like fibers of sorbent material 
               28  skin of sorbent material  24   
               30  semi-circular pocket of sorbent material 
               32  stitches on semi-circumference of pocket  30   
               34  pocket  30  opening to accommodate disc  16   
               36  straight edges of pocket  30   
               37  overlapping flap of pocket  30   
               38  sides of pocket  30   
               39  overlapped flap of pocket  30   
               40  stitches in pocket  30  passing through disc slots  42   
               42  slots in disc  16   
               44  opening in pocket  30  to accommodate shaft  20   
               45  arrow showing direction of disc rotation 
               46  hydraulic motor of disc skimmer  10   
               48  sleeve 
               50  bearing 
               52  nut 
               54  disc scrapers 
               56  side edges of scrapers  54   
               58  trough collection members of disc skimmer  10   
               60  disc spacers supporting trough collection members  58   
               62  scraper  54  mounting support 
               64  pop rivets connecting scraper  54  and support  62   
               66  sump of disc skimmer  10   
               68  trough support rods 
               70  pump 
               72  discharge conduit of disc skimmer  10   
               74  relief valve 
               100  drum skimmer 
               101  flotation means (pontoons) of drum skimmer 
               102  eyelets for towing 
               103  sloped forward portions of pontoons  101   
               104  drum 
               105  handles 
               106  axis of rotation of drum  104   
               108  rotating shaft for drum  104   
               110  hydraulic motor of drum skimmer  100   
               112  gear reducer 
               114  drum surface 
               116  sorbent material covering drum surface  114   
               118  skin of sorbent material  116   
               120  overlapping flap of material  116   
               122  overlapped flap of material  116   
               124  strip of double-sided adhesive tape attaching overlapped flap  122  to drum surface  114   
               125  Velcro® strips 
               126  drum scraper 
               128  mounting bracket for scraper  126   
               130  pop rivets connecting scraper  126  and bracket  128   
               132  eyelets in bracket  128   
               134  edge of scraper  126   
               136  trough collection member of drum skimmer  100   
               138  discharge line of drum skimmer  100   
               200  fully circular pocket 
               201  skin side of pocket  200   
               202  pocket  200  opening to accommodate disc  16   
               204  stitches in perimeter of pocket  200   
               206  flap portions of pocket  200   
               208  stitches in pocket  200  through disc slots  42