Self-cleaning fuel oil strainer

Details Self-cleaning fuel oil strainer Self-cleaning fuel oil strainer

1999-10-13

2001-01-23

Savage, Matthew O. (Department: 1723)

Liquid purification or separation

Processes

Separating

C210S393000, C210S397000, C210S398000, C210S402000, C210S784000

Reexamination Certificate

active

06177022

ABSTRACT:

SPECIFICATION
BACKGROUND OF THE INVENTION
This invention relates generally to filter devices and, more particularly, to fuel system filters for small particulate contaminants.
It is well-known that the mechanical cleaning of a filter surface can be accomplished by having a brush or scraper drag along the filter surface where deposits have accumulated. In certain configurations, the brush or scraper is mounted at one end between two walls but with a significant portion of the brush or scraper projecting beyond the walls. Such configurations are shown in U.S. Pat. No. 148,557 (Gillespie et al.); U.S. Pat. No. 556,725 (Farwell); U.S. Pat. No. 740,574 (Kohlmeyer) and U.S. Pat. No. 793,720 (Godbe). In conventional filter systems, the particulate contaminants are driven off the filter surface and are deposited in a hopper or tank along with the fluid being filtered, thus discarding large amounts of the fluid being filtered.
The use of a brush, or high speed cleaning spray, disposed between a pair of walls for cleaning a cylindrical filter is known in the art, as is disclosed in U.S. Pat. No. 5,423,977 (Aoki et al.) and U.S. Pat. No. 5,595,655 (Steiner et al.) and Swiss Patent No. 22,863 (Zingg). Another variation employs a backwash that drives the particulate contaminants off of the cylindrical filter, as is disclosed in U.S. Pat. No. 3,338,416 (Barry).
One desirable use for fuel oil filter systems of the present invention is in ships. Prior art ship fuel oil systems use conventional filter cartridges for cleaning the fuel in-line. However, these filter cartridges require frequent replacement which, in turn, requires the fuel flow to be interrupted during replacement. Interruption of the fuel oil flow will shut down the ship's main engines, thereby rendering the ship incapable of maneuvering. This can be catastrophic where the ship is in tight quarters, e.g., during docking or navigating through narrow passageways, or during storms, or during battle with regard to warships.
Furthermore, there are additional costs of having to store sufficient replacement cartridges onboard, the logistics involved in shipping and disposing the cartridges to and from the ship, and the labor costs involved in replacing the cartridges.
In addition, shipboard fuel oil straining is a specialized straining process. In particular, the fuel oil flow is initially pre-strained for gross particulate contaminants, such that any particulate contaminants remaining in the fuel oil flow are extremely small (e.g., <100 microns, with a large percentage being less than 25 microns). As a result, where these small particulate contaminants are captured by a downstream strainer (e.g., a wedge wire screen strainer), both on and within the strainer surface, and then later dislodged during the strainer cleaning process, these extremely small particulate contaminants do not fall by gravity toward a drain but remain suspended in the fuel oil and will re-attach to the strainer surface. Therefore, there remains a need for a cleaning device that can dislodge such extremely small particulate contaminants off of the downstream strainer surface, as well as from within the strainer surface, and then ensure that these particulate contaminants flow out through the drain rather than re-attaching to the strainer surface.
Thus, there is a need for an improved system for removing undesired particulate contaminants from a fuel oil flow and without interrupting that fuel oil flow to the engines, while minimizing the amount of fluid removed therewith. It is to just such a system that the present invention is directed.
OBJECTS OF THE INVENTION
Accordingly, it is the general object of the instant invention to provide a fuel oil cleaning device that overcomes the problems of the prior art.
It is a further object of this invention to provide a fuel oil cleaning device that permits continuous fuel oil flow even during the cleaning process.
It is a further object of this invention to provide a fuel oil cleaning device that removes small particulate contaminants from a strainer surface, and from within the strainer surface, and ensures that when these small particulate contaminants are dislodged from the strainer during cleaning that they enter a drain rather than re-attaching to the strainer surface.
It is still yet another object of this invention to provide a fuel oil cleaning device that generates a high velocity flow of dislodged particulate contaminants away from the strainer and into a drain.
It is a further object of this invention to provide a fuel oil cleaning device that minimizes the amount of fuel oil that must be discarded during cleaning.
It is still yet a further object of this invention to eliminate the need for frequent replacement of the fuel oil filter.
It is still another object of this invention to minimize the costs associated with frequent fuel oil filter replacements.
It is still yet even another object of this invention to improve the efficiency of particulate removal.
It is still yet another object of this invention to provide a fuel oil filter that can be self-cleaned with the use of a reverse flow of clean fuel oil.
It is even yet another object of this invention to provide a self-cleaning fuel oil filter system that permits the fuel oil filter element to remain stationary during cleaning.
SUMMARY OF THE INVENTION
These and other objects of the invention are achieved by providing a fuel oil cleaning device disposed within a continuous fuel oil flow having particulate contaminants therein. As mentioned earlier, the particulate contaminants that need to be removed from the fuel oil flow are extremely small, less than 100 microns, and a large percentage of these less than 25 microns, therefore do not settle out by gravity. The invention of the present application is well-suited to removing these small particulate contaminants from the fuel oil flow and into a drain. The cleaning device comprises a porous member in fluid communication with the fuel oil flow such that the fuel oil flow enters the porous member through a first porous member surface and exits through a second porous member surface and wherein the fuel oil flow deposits the particulate contaminants on the first porous member surface. The cleaning device further comprises particulate-removing means (e.g., a brush, a scraper, or equivalent device, or a reverse flow of clean fuel oil, or any combination of these for removing particulate contaminants from the porous member) disposed to be in close proximity with the first porous member surface for removing particulate contaminants from the first porous member surface along substantially the entirety of the length of the first porous member surface. The cleaning device also comprises a drive mechanism for displacing the porous member such that the particulate-removing means dislodges the particulate contaminants from the first porous member surface during the displacement. In addition, the cleaning device includes a pair of flow confining walls disposed to be in close proximity with the first porous member surface along substantially the entirety of the length of the first porous member surface for defining a chamber for confining the removed particulate contaminants therein. The particulate-removing means is positioned within the chamber. The cleaning device also comprises a drain that is in communication with the chamber and through which the dislodged particulate contaminants are removed when the drain is opened. The cleaning device further comprises a partition that divides the chamber into a first subchamber and a second subchamber along the length of the chamber and wherein the drain is in communication with the second subchamber. The partition includes a plurality of apertures for passing the dislodged particulate contaminants from the first subchamber into the second subchamber. The plurality of apertures is of sufficient area to generate a rapid velocity of dislodged particulate contaminants from the first subchamber to the second subchamber.
The term continuous fuel oil flow is defined as a fuel oil

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