Patent Application
20130098823
1. Field of the Invention
This invention relates generally to skimming devices for skimming incremental amounts of a liquid from a liquid surface and, in particular, to buoyant skimming devices that are capable of floating at the surface of a liquid environment to which the buoyant skimming devices are applied for the purpose of removing a selective increment of liquid at the surface of the liquid environment.
2. Discussion of the Prior Art
There are a variety of circumstances in which it is desired to remove from the surface of a body of a first liquid at least a portion of a second liquid that is floating on or is suspended at the surface of the body of the first liquid. In many instances, the second liquid can comprise a contaminant that is disposed of after being removed from the body of the first liquid. For example, the removal of oily materials from parts washers before the oily materials can contaminate parts as they are removed from a wash tank, the removal of oils, greases and fats from the wastewater streams of food processing facilities, the removal of heavy oil and grease accumulations present in steel mill scale pits, the removal of floating oils that contaminate natural bodies of water and the removal of oil, fuel and other hydrocarbon liquids from wells all comprise well-known oil-removal operations.
Many manufacturing and processing facilities include systems in which waste oils and coolants collect in a central tank or sump. Thus, in an industrial operation such as grinding, milling or turning for example, liquid coolants, sometimes referred to as cutting oils, metalworking fluids or metal removing fluids, are employed for the purpose of enhancing the grinding, milling or turning operation. During the operation, the coolant can become contaminated with, for example, oils that are used to lubricate components of the machinery involved in the operation, protective oil film with which the work piece is coated and hydraulic oil leaks. These liquid contaminants, typically, are referred to as tramp oils and because the tramp oils have a lesser specific gravity than the coolant the tramp oils will float on the coolant in the sump to which the tramp oils and coolant are directed and in which the tramp oils and coolant accumulate. Removing the tramp oils without entraining significant quantities of coolant in the tramp oils can reduce the cost of disposal of the tramp oils. In certain instances, however, the tramp oils can include important quantities of entrained coolant, and in those instances it can be advantageous to remove the tramp oils and the entrained coolant and deliver the tramp oils and entrained coolant to a liquid separator or coalescing equipment for the purpose of recovering the entrained coolant from the tramp oils.
Numerous types of skimming devices are known for separating oily liquids from the underlying liquids on which the oily liquids float. For example, in instances in which tramp oils are to be removed from a coolant, tramp oil skimmers are used to separate the tramp oils from the coolant. The tramp oil skimmers can comprise slowly rotating disks, tubes or belts that are partially submerged below the coolant. As the disks, tubes or belts rotate through the coolant and the tramp oils floating on the coolant, the tramp oils, but not the coolant to any significant degree, will cling to the disks, tubes or belts. The disks, tubes or belts carrying the clinging tramp oils will pass by a wiper mechanism or the like that scrapes the tramp oils from the disks, tubes or belts after which the tramp oils are directed to a container at which the tramp oils are collected for disposal.
Floating oil skimmers, sometimes referred to as floating suction skimmers, also can be provided for removing the oily material that floats on another liquid. Again with reference to an operation in which tramp oils and a coolant are collected in a common sump and the tramp oils float on the coolant, the floating oil skimmers are configured to float at the surface of the tramp oils and take in, usually under the influence of a pump, the liquid materials that are located there. It can be the case that the floating oil skimmers will draw away not only the tramp oils but some coolant as well. Consequently, in such instances, the tramp oils and the entrained coolant captured by the floating oil skimmers can be directed to a liquid separator or coalescing device that separates the tramp oils and the coolant.
The following sets forth a simplified summary of examples of the present invention for the purpose of providing a basic understanding of selected aspects of the invention. The summary does not constitute an extensive overview of all the aspects or embodiments of the invention. Neither is the summary intended to identify critical aspects or delineate the scope of the invention. The sole purpose of the summary is to present selected aspects of the invention in a concise form as an introduction to the more detailed description of the embodiments of the invention that follows the summary.
According to one aspect of the invention, a buoyant skimming device includes an enclosure that bounds an interior space that is configured to hold a liquid within the enclosure and to be in fluid communication with means for withdrawing from the interior space the liquid held in the interior space. A portion of the enclosure comprises a weir that is configured to provide access to the interior space for liquid at the exterior of the enclosure. The weir is mounted with respect to a body portion of the enclosure for pivotal movement inwardly of the body portion of the enclosure into the interior space.
According to another aspect, the enclosure includes an upper section that is inclusive of the interior space and a lower section that is located below the interior space and the lower section includes weighting elements in an amount sufficient to establish a center of gravity for the buoyant skimming device that is within the lower section of the buoyant skimming device.
According to a further aspect, an opening in the body portion of the enclosure provides for the fluid communication between the interior space and the means for withdrawing from the interior space the liquid held in the interior space. A screening element is located within the interior space through which liquid within the interior space must pass in flowing from the interior space to the opening in the remainder of the enclosure.
According to an additional aspect, the weir includes an upper edge that is configured to allow liquid at the exterior of the enclosure to pass over the upper edge of the weir when the weir is pivotally moved inwardly of the body portion of the enclosure into the interior space.
According to yet another aspect, the weir includes a pair of oppositely arranged side edges and a bottom edge that are configured to be in engagement with the body portion of the enclosure whenever the weir is pivotally moved inwardly of the body portion of the enclosure into the interior space.
According to still another aspect, the weir has a greater buoyancy than the body portion of the enclosure.
The foregoing and other aspects of the present invention will be apparent to those skilled in the art to which the invention relates based on the detailed descriptions of examples of aspects and embodiments of the invention that follow with reference to the accompanying drawings, wherein the same reference numerals are used in the several figures to refer to the same parts, elements and components and in which:
Examples of embodiments that incorporate one or more aspects of the present invention are described below with references, in certain respects, to the accompanying drawings. These examples are not intended to be limitations on the present invention. Thus, for example, in some instances, one or more examples of the present invention described with reference to one aspect or embodiment can be utilized in other aspects and embodiments. In addition, certain terminology is used herein for convenience only and is not to be taken as limiting the present invention.
The references to a “buoyant skimming device” that follow, including such references in the claims, are intended to be inclusive of any device that floats at the surface of a liquid environment to which the device is applied for the purpose of removing a selective increment of liquid at the surface of the liquid environment.
Also as can be seen in
The interior space 14 is configured to be in fluid communication with means 34 for withdrawing from the interior space the liquid held in the interior space. The means 34 can include a pump or any other device capable of functioning to draw out of the interior space 14 the liquid held in the interior space. For example, the means 34 can comprise a gravity feeding mechanism for drawing out the liquid held in the interior space 14 as will be familiar to those having ordinary skill in the art. In the example of the invention shown in the figures, an opening 35 in the rear panel 22 of the body portion 12 of the enclosure provides for the fluid communication that exists between the interior space 14 and the means 34 for withdrawing from the interior space the liquid held in the interior space. As shown in
A screening element 38 can be located within the interior space 14 through which liquid within the interior space 14 must pass in flowing from the interior space to the opening 35 in the body portion 12 of the enclosure 10. The function of the screening element 38 is to screen out any particulate matter that may be present in the liquid held within the interior space 14. A first slot 39 can be provided within the first side panel 16 and a second slot 40 can be provided within the second side panel 18 into which the screening element 38 can be inserted and held in place and from which the screening element can be removed for the purpose of cleaning the screening element for example.
The weir 41 is mounted with respect to the body portion 12 of the enclosure 10 for pivotal movement of the upper portion of the weir inwardly of the body portion 12 of the enclosure 10 into the interior space 14. As shown in the example of the invention illustrated in the figures, the weir 41 includes near its bottom a weir through-hole 42 that is in alignment with a first side panel through-hole 43 located near the bottom of the first side panel 16 and a second side panel through-hole 44 located near the bottom of the second side panel 18. An elongated screw 46 extends through the weir through-hole 42, through the first side panel through-hole 43 and through the second side panel through-hole 44 and the weir 41 is secured to the body portion 12 of the enclosure 10 by means of the screw head 48 of the elongated screw 46 and a nut 50 threaded to the end of the elongated screw 46 opposite the screw head 48. The nut 50 is screwed to the end of the elongated screw 46 opposite the screw head 48 only with a sufficient retention force to maintain the weir 41 in place when no force is being applied to the weir 41 that would cause the upper portion of the weir 41 to pivot inwardly into the interior space 14. However, the retention force is insufficient to prevent the weir from pivoting inwardly into the interior space 14 when a force, such as the hydraulic pressure of the liquid environment in which the skimming device is located, is applied to the weir in the direction of the interior space 14.
As best seen in
For reasons discussed below in connection with a description of the operation of the buoyant skimming device, the weir 41 can be given greater buoyancy than the body portion 12 of the enclosure 10. This can be accomplished as illustrated in the aspect of the invention shown in the figures by attaching to the interior surface 69 of the weir 41 an enclosed hollow cylinder 80 that can be made of a plastic material for example.
In one aspect of the operation of the buoyant skimming device, the device, with the means 34 turned off, is placed in a liquid environment wherein a first liquid is supported or is floating on a second liquid that has a specific gravity that is greater than the first liquid with the objective of removing at least a portion of the first liquid. Sufficient weighting elements 33 are added to the cavity 30 of the enclosure 10 so that the buoyant skimming device will penetrate the surface of the liquid environment to a depth such that at least a portion of the depth of the first liquid will be in contact with the exterior surface 68 of the weir 41. The pressure exerted by the liquid that engages the exterior surface 67 of the weir 41 will cause the upper margin 66 of the weir 41 to pivot around the elongated screw 46 inwardly of the interior space 14 allowing the liquid to spill over the upper margin 66 of the weir 41 and into the interior space 14. The upper margin 66 of the weir 41 will continue to pivot around the elongated screw 46 and the liquid will continue to spill over the upper margin 66 of the weir 41 until the height of the liquid in the interior space 14, nominally, is at the same level as the height of the liquid at the exterior of the interior space. Thus, the weir 41 is configured to provide access to the interior space 14 for liquid at the exterior of the enclosure 10.
Once the means 34 is activated and the liquid in the enclosed space 14 begins to be withdrawn from the enclosed space, the level of the liquid in the enclosed space will tend to fall causing a pressure differential to be created between the liquid at the exterior of the skimming device and the liquid within the enclosed space 14. The pressure differential will cause the top margin 66 of the weir 41 to pivot further inwardly into the enclosed space resulting in additional liquid from the exterior of the skimming device spilling over the top margin 66 and into the enclosed space 14. Once sufficient liquid has spilled into the enclosed space 14, the liquid levels at the exterior of the skimming device and within the enclosed space 14 will be substantially the same so that the pressure at the exterior of the skimming device and the pressure within the enclosed space 14 will be substantially equal and the weir 41 will not pivot inwardly any further except as liquid is withdrawn from the enclosed space 14. In effect, a steady state of operation will be established such that the weir 41 will tend to be maintained in a position such that the levels of the liquids at the exterior of the skimming device and within the enclosed space 14 will be maintained at the same heights as liquid continues to be withdrawn from the enclosed space 14. By arranging for the weir 41 to be more buoyant than the body of the enclosure 12, such as by attaching the hollow cylinder 80 to the weir, the weir under the influence of the pressure forces at the exterior of the skimming device and within the enclosed space 14 will pivot inwardly and outwardly more freely and facilitate the operation of the skimming device.
The acute edges 70 and 71 of the weir 41 can provide two benefits in connection with the operation of the skimming device. First, the contact between the acute edge 70 and the interior surface 17 of the first side panel 16 and the contact between the acute edge 71 and the interior surface 19 of the second side panel 18 will minimize the amount of the fluid that flows into the interior space 14 around the edges of the weir 41. At the same time, the essentially line contact between the acute edges 70 and 71 of the weir and the interior surfaces 17 and 19, respectively, minimize the surface area of the weir that is in contact with the interior surfaces so as to reduce the likelihood that the weir will freeze or be stuck to the interior surfaces and be unable to function as required. Although not required, the upper edge 15 of the first side panel 16 and the upper edge 21 of the second side panel 18 are provided in the aspect of the invention illustrated in the figures with arcuate profiles.
While the present invention has been described above and illustrated with reference to certain embodiments thereof, it is to be understood that the invention is not so limited. Thus, as noted above, the various aspects of the present invention can have applications in contexts other than with machining operations. In addition, modifications and alterations of the aspects of the invention described herein will occur to those skilled in the art upon reading and understanding the specification, including the drawings. The present invention is intended to cover and include any and all such modifications and variations to the described embodiments that are encompassed by the following claims.
