FIELD

The present invention relates to a filter and, more particularly, a filter for removing contaminants from water. BACKGROUND

There are many situations that require cleaning of water. For example, extraction of oil and gas from beneath the seafloor involves water which is mixed with oil, gas, and solid contaminants. The water mixture is referred in the art as produced water. The oil and gas must be removed from the produced water before the oil and gas is transported to a refinery. Also, oil, grease and other hydrocarbons are unavoidably spilled on work decks of offshore drilling and production platforms. These and other contaminants, such as dirt, are washed off the decks by water or rain into collection vessels where the contaminants are removed so that they do not pollute the ocean.

The amount of available space can be quite limited on work decks of offshore drilling rigs and other environments. As such, there is need to reduce the amount of space occupied by filtering equipment in such environments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing an example filter.

FIG. 2 is an exploded view showing example components within the filtration chamber of the filter, including a movable compression plate located above a base plate.

FIGS. 3A and 3B show the components of FIG. 2 assembled together.

FIG. 4 is an exploded view showing example components that are the same as those in FIG. 2 except the movable compression plate is located below the base plate.

FIGS. 5A and 5B show the components of FIG. 4 assembled together.

FIGS. 6A and 6B are a cross-section views showing components of the filter at line 6-6 of FIG. 1.

FIG. 7A is a cross-section view showing components of the filter at line 7A--7A of FIG. 1.

FIG. 7B is a cross-section view showing components of the filter at line 7B--7B of FIG. 1. All drawings are schematic illustrations and the structures rendered therein are not intended to be in scale.

SUMMARY

Briefly and in general terms, the present invention is directed to a filter and a filtering method.

In aspects of the invention, a filter comprises a filtration chamber configured to carry liquid, a lead screw, a motor, and a compression plate. The lead screw comprises a lower rod and an upper rod, the upper rod extending through a sealed aperture of the filtration chamber, the lower rod extending from the upper rod and disposed within the filtration chamber. The motor is coupled to the upper rod and is configured to rotate the upper rod and the lower rod in a first rotation direction and a second rotation direction opposite the first direction. The compression plate is within the filtration chamber and is coupled to threads of the lower rod of the lead screw. The compression plate moves down when the motor rotates the lower rod in the first direction, and the compression plate moves up when the motor rotates the lower rod in the second direction.

In aspects of the invention, a filtering method comprises pumping liquid into a filtration chamber, and using a motor to rotate a lower rod and an upper rod of a lead screw, the upper rod coupled to the motor outside of the filtration chamber and extending through a sealed aperture of the filtration chamber, the lower rod extending from the upper rod and comprising threads coupled to a compression plate within the filtration chamber. The rotation includes rotating the lower rod and the upper rod in a first direction and in a second direction opposite the first direction. The compression plate moves down within the filtration chamber as a result of rotation in the first direction. The compression plate moves up within the filtration chamber as a result of rotation in the second direction.

The features and advantages of the invention will be more readily understood from the following detailed description which should be read in conjunction with the accompanying drawings.

DETAILED DESCRIPTION

The terms "up", "upper," "upward," "lower," "down," "downward," and the like refer to the orientation of components in relation to one another as illustrated in the figures. These terms should not be interpreted as limiting the scope of the invention to a particular orientation of the filter. For example, it is to be understood that when the filter is inverted from what is shown in the figures, an "upper" component may actually be located below a "lower" component.

Referring now in more detail to the drawings for purposes of illustrating aspects of the invention, wherein like reference numerals designate corresponding or like elements among the several views, there is shown in FIG. 1 example filter 10 comprising filtration chamber 12 configured to carry a liquid, such as water, which has been pumped into filtration chamber 12. Filter 10 comprises lead screw 14, which comprises lower rod 16 and upper rod 18. Upper rod 18 extends from an area above filtration chamber 12 into a volume within filtration chamber 12. Upper rod 18 passes through sealed aperture 20 of filtration chamber 12. Lower rod 16 extends from upper rod 18 and is disposed within the same volume of filtration chamber 12 occupied by upper rod 18. Upper rod 18 and lower rod 16 rotate simultaneously together. Lower rod 16 rotates about its central axis 17. Upper rod 18 rotates about its central axis 19. Central axis 17 and central axis 19 are coincident. Upper rod 18 and lower rod 16 may be two distinct parts which are secured to each other, or they may integral with each other to form a unitary structure.

Filter 10 comprises motor 22 which is coupled to upper rod 18 and is configured to rotate upper rod 18 and lower rod 16, simultaneously, in first rotation direction 24 and second rotation direction 26 opposite first direction 24. For example, first rotation direction 24 can be counter-clockwise, and second rotation direction 26 may be clockwise. Alternatively, first rotation direction 24 can be clockwise, and second rotation direction 26 may be counter-clockwise.

Filter 10 comprises control unit 28 which is connected to motor 22. Control unit

28 may comprise a microcontroller having circuitry and a software program.

Microcontroller transmits control signals to motor 22 to control the timing of rotation and the direction of rotation of upper rod 18 and lower rod 16.

Filter 10 comprises compression plate 30 located within filtration chamber 12. Compression plate 30 is coupled to helical threads 32 (FIG. 2) of lower rod 16.

Compression plate 30 include holes 33 that allow movement of water and other substances through compression plate 30. For example, compression plate 30 may be a mesh of metal wires or a perforated plate made of a flat sheet of metal or other material. Compression plate 30 is movable within filtration chamber 12. Compression plate 30 moves down linearly when motor 22 rotates lower rod 16 in first direction 24. Compression plate 30 moves up linearly when motor 22 rotates lower rod 16 in second direction 26. When lower rod 16 rotates, lower rod 16 does not move linearly with compression plate 30. When lower rod 16 rotates, compression plate 30 does not rotate. Compression plate 30 may be prevented by rotating by a linear guide rail within filtration chamber 12.

Filter 10 comprises base plate 34 located within filtration chamber 12. Base plate 34 include holes 36 that allow movement of water and other substances through base plate 34. For example, base plate 34 may be a mesh of metal wires or a perforated plate made of a flat sheet of metal or other material. Base plate 34 is located below

compression plate 30, as illustrated in FIGS. 1, 2, 3A, and 3B.

Base plate 34 is not movable within filtration chamber 12. Base plate 34 is stationary when compression plate 30 moves. For example, as shown in FIGS. 3A and 3B, compression plate 30 may move downward, toward base plate 34, when motor 22 rotates lower rod 16 in first direction 24. Compression plate 30 may move upward, away from base plate 34, when motor 22 rotates lower rod 16 in second direction 26.

Alternatively, as shown in FIG. 4, base plate 34 can be located above

compression plate 30. For example, as shown in FIGS. 5A and 5B, compression plate 30 may move upward, toward base plate 34, when motor 22 rotates lower rod 16 in first direction 24. Compression plate 30 may move downward, away from base plate 34, when motor 22 rotates lower rod 16 in second direction 26.

Lead screw 14 is used instead of a hydraulic ram that includes a plunger having one end connected to compression plate 30. The plunger would move linearly up and down to move compression plate 30, which would then require a significant amount of vertical clearance above filtration chamber 12. Lead screw 14 does not move linearly up and down, which reduces the spatial volume required by filter 10 as compared to a filter using a hydraulic ram. Use of lead screw 14 can be advantageous when filter 10 is used on offshore drilling rigs and other environments where space is limited.

Referring again to FIG. 1, filtration chamber 12 comprises chamber wall 40 and chamber cover 42 connected to chamber wall 40. Base plate 34 may be secured one or both of chamber wall 40 and chamber cover 42 to keep base plate 34 stationary while compression plate 30 moves. Chamber wall 40 may extend beneath base plate 34, forming a floor of filtration chamber 12. Chamber wall 40 and chamber cover 42 may be two distinct parts which are secured to each other. For example, chamber cover 42 may be secured to chamber wall 40 with latches configured to allow removal of chamber cover 42 from chamber wall 40. Alternatively, chamber wall 40 and chamber cover 42 may be integral with each other to form a unitary structure.

Chamber wall 40 surrounds compression plate 30 and base plate 34. Sealed aperture 20 is on chamber cover 42. The segment of upper rod 18 that passes through chamber cover 42 may be a smooth cylinder. For example, it is possible for that segment of upper rod 18 to have no helical threads. Chamber cover 42 and chamber wall 40 are configured to maintain interior air pressure of filtration chamber 12 greater than the ambient air pressure outside of filtration chamber 12. Maintaining water in filtration chamber 12 at an elevated pressure allows the water to flow through filtration chamber 12 at a relatively high rate.

As shown in FIG. 6A, upper rod 18 comprises cylindrical bearing surface 44. Filtration chamber 12 comprises bearing seal 46 around sealed aperture 20. Bearing seal 46 contacts cylindrical bearing surface 44 of upper rod 18. Bearing seal 46 presses against cylindrical bearing surface 44, with or without lubrication between bearing seal 46 and cylindrical bearing surface 44, while cylindrical bearing surface 44 rotates due to rotation by motor 22 of upper rod 18 of lead screw 14. Bearing seal 46 is configured to maintain interior air pressure of the filtration chamber above ambient air pressure outside of the filtration chamber. The pressure difference may be maintained by a tight fit between bearing seal 46 and cylindrical bearing surface 44.

As shown in FIG. 6B, the pressure difference may be maintained by sealing device 48 located at another portion of bearing seal 46. Sealing device 48 may form part of bearing seal 46 or cylindrical bearing surface 44. Sealing device 48 may be seated in an annular groove formed into interior surface 50 (FIG. 6 A) of bearing seal 46. Additionally or alternatively, sealing device 48 may be seated in an annular groove formed into cylindrical bearing surface 44 of upper rod 18. Sealing device 48 may be any one or a combination of a labyrinth seal, O-ring gasket, and bushing.

As shown in FIGS. 1, 2, and 4, filter 10 comprises filter media shield 52 at interface 53 (labeled in FIG. 1 and 8A) between compression plate 30 and threads 32 of lower rod 16. A portion of filter media shield 52 has been removed from FIG. 1 to illustrate a portion of lower rod 16 inside filter media shield 52. Lower rod 16 rotates within filter media shield 52. Filter media shield 52 does not rotate when lower rod 16 rotates. Referring to FIGS. 2, 4, 7 A, and 7B, filter media shield 52 comprises shield wall 54 and wipers 56 secured to shield wall 54. Wipers 56 prevent material, such as filter media and any other objects, from entering interface 53 and possibly interfering with rotation of lower rod 16 and movement of compression plate 30.

Slots 58 are formed through shield wall 54. For each slot 58, compression plate

30 comprises connector 60 that extends through slot 58 and mates with helical threads 32 of lower rod 16. Each connector 60 may include threads having a shape that corresponds to that of helical threads 32 to allow connector 60 to mate with helical threads 32. Connector 60 may be a distinct component that is secured to a region of compression plate 30 adjacent to interface 53 (FIG. 1). Alternatively, connector 60 may be an integral part of compression plate 30 so as to form a unitary structure.

As shown in FIG. 7A, wipers 56 cover slots 58. As shown in FIG. 7B, each wiper 56 may bend around connector 60 to allow connector 60 to contact and mate with helical threads 32 of lower rod 16. Wipers 56 may be secured to opposing edges 62 of slot 58. For example, wipers 56 may comprise a flexible strip of material, such a rubber, that covers slot 58 and is secured to opposing edges 62 of slot 58. Additionally or alternatively, each wiper 56 may comprise bristles that extend from shield wall 54. For each slot 58, the bristles cover slot 58 and bend around connector 60 to allow connector 60 to contact and mate with helical threads 32 of lower rod 16. The bristles may be secured to opposing edges 62 of slot 58.

Two slots 58 and two connectors 60 are illustrated. Alternatively, there may be only a single slot and a single connector, or there may be a more than two slots and a corresponding number of connectors.

Filter 10 may be used to remove solids and other contaminants from water. For example, produced water may contain solid and hydrocarbon contaminants, and filter 10 may be used to remove the solid contaminants to facilitate subsequent removal of hydrocarbon contaminants. As shown in FIG. 1 , filter media 70 is contained between compression plate 30 and base plate 34. Filter media 70 may include a bundle of synthetic fibers. The fibers may include polyvinylidene chloride fibers,

polyvinylchloride fibers, polyethylene fibers, other synthetic polymer fibers, and/or combinations thereof. By movement of compression plate 30 toward base plate 34, filtration chamber 12 compress filter media 70 to allow entrapment of solids 72 in filter media 70. By movement of compression plate 30 away from base plate 34, filtration chamber 12 decompress filter media 70 to allow flushing of solids out from filter media 70.

When filtration chamber 12 is in a compressed state, as shown in FIGS. 3B and 5B, filter media 70 are packed together and thereby form a network of fibers through which water must pass. The network of fibers trap dirt and other solids. Over time, the network of fibers becomes filled with solids, which reduces filtering efficiency. Solids can be readily removed from the fibers by arranging filtration chamber 12 in an enlarged state, as shown in FIGS. 3A and 3B. When filtration chamber 12 is in the enlarged state, filter media 70 may separate from each other. The density of fibers is reduced, which allows solids to be released from filter media 70 when clean flushing water is injected into filtration chamber 12.

Filtration chamber 12 includes inlet 74 and outlet 78. When filtration chamber 12 is in its compressed state, inlet 74 delivers contaminated water into plenum 76 of filtration chamber 12. Contaminated water contains solids and optionally hydrocarbon contaminants entrained and/or emulsified in the water. Plenum 76 is located below filter media 70. There is no filter media in plenum 76. Filtered water flows out of outlet 78. Outlet 78 is located above filter media 70.

When filtration chamber 12 is in its enlarged state, inlet 74 delivers flushing liquid into plenum 76 of filtration chamber 12. Flushing liquid is water that does not contain solids. The flushing liquid draws solid contaminants out of filter media 70. The flushing liquid and solid contaminants flow out of outlet 78.

While several particular forms of the invention have been illustrated and described, it will also be apparent that various modifications can be made without departing from the scope of the invention. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the invention. Accordingly, it is not intended that the invention be limited, except as by the appended claims.