Patent Application
20150090655
The present disclosure relates to a filter assembly of the type housed in a pressure vessel for providing filtering of fluid flowing in a pressurized fluid system. Such filter assemblies are employed in water treatment systems and systems employing hydraulic or other fluids in a closed system where it is necessary to remove contaminants from the fluid in order to protect the system components. Examples of such systems are those employed for filtering hydrocarbon fluids in crude oil refining where system pressures in the range of 300-600 psi and fluid temperatures of 750° F. are encountered in addition to relatively high volume flow of such fluids.
The more typical filtration systems employ generally cylindrical pressure vessels oriented with their axis of the cylinder disposed vertically requiring support structure, such as legs welded thereon, which raised the height of the vessel from the support surface or floor, thus making lid or closure removal difficult. Therefore, it has been desired to have the pressure vessel oriented with the axis of the cylindrical configuration disposed horizontally.
Heretofore, where more than one filter element was required, separate pressure vessels have been employed with provisions made for isolating the pressure vessels individually for performing regeneration of the element in the filter tube for each pressure vessel. Such arrangements require a relatively large physical layout and additional valving arrangements. This requirement for multiple pressure vessels has made such arrangements prohibitively costly and unworkable where the space available is limited.
One known technique employed for internal backwashing has employed a rotating arm with a nozzle in the form of a narrow slot on the end of an arm which can be positioned progressively at selected regions of the filter media and a suction applied through the arm to the slot to remove contaminants from a narrow band of the filter media. This technique requires a suction pump and additional complex controls and is thus costly to employ in systems requiring a high flow volume for filtration.
Another technique employed in present internal fluid filtering arrangements is that of employing a single pressure vessel with multiple filter media tubes, fluidly connected to have the interior of the tube as the upstream side, with a movable backwash tube disposed therein. The backwash tube may be moved for connecting the element tube to a drain at a substantially lower pressure than the filtrate in the vessel thus enabling backwashing by movement of the backwash tube.
External backwashing with a clean fluid separate from the fluid being filtered, which may include solvents, has been employed and has the advantage that a higher pressure may be employed to more effectively remove caked and large particle size contaminants; and, a more intense pressure pulse applied to backwashing to break loose heavy contaminants.
However, where it has been desired to provide an external source of backwashing fluid, particularly with fluid cleaner than the filtrate, such an arrangement was only possible where single filter elements were employed in each of the pressure vessels.
It has thus been desired to provide a way or means of housing a plurality of tubular filter media elements filtering flow from the exterior to the interior and in a single pressure vessel and providing for internal backwashing of the individual filter media elements by utilizing the filtered fluid in the pressure vessel for selectively individually backwashing each of the multiple filter media elements in a manner which accommodates and maintains flow through the remaining filter media elements.
The present disclosure describes and illustrates a fluid filtration assembly for filtering fluid flowing in a pressurized fluid system and utilizes a single pressure vessel which may be of cylindrical configuration for connection in the system to receive contaminated fluid at the vessel inlet and discharge filtered fluid at the outlet to continue in the system. The filtration assembly of the present disclosure describes a single pressure vessel oriented horizontally having a plurality of shroud tubes each with a plurality of tubular filter media elements or “sticks” disposed therein of the type having the exterior of the media element as the upstream side and the interior as the downstream side. One end of each shroud tube is connected to a bulkhead in the pressure vessel such that fluid from the inlet flows through an aperture in the bulkhead to the interior of the shroud tube. The opposite end of the shroud tube is sealed by a cover plate such that the interior thereof communicates exclusively through an aperture in the cover plate permitting flow of filtrate to the vessel outlet.
A rotating tubular drain arm is provided in the region of the pressure vessel between the bulkhead and a drain outlet in the pressure vessel. The tubular drain arm has a first open end disposed for, upon rotation, to be selectively and progressively positioned coincident with an aperture in the bulkhead for communicating flow to the interior of one of an inner array of the shroud tubes. A second open end of the drain arm is disposed for, upon rotation of the drain arm, to be selectively and progressively positioned coincident an aperture in the bulkhead for communicating flow to the interior of one of an outer array of shroud tubes surrounding the inner array. The apertures in the bulkhead are offset from the center of the shrouds and tangentially adjacent the inner periphery of the shrouds. A drain port in the drain arm is provided intermediate the first and second ends; and, the drain arm is disposed on a rotatable fluid coupling communicating the drain port in the drain arm with the drain port in the fluid vessel. A motor drive shaft is connected through the rotatable coupling to the rotating drain arm. Brackets are provided on the pressure vessel for supporting it in a horizontal orientation.
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An outlet fitting 34 is provided in the pressure vessel 12 and defines an outlet port or passage 36. A mounting flange 38 having an annular configuration is provided on the interior of the pressure vessel 12 between the outlet port 36 and the inlet port 18.
A bulkhead or backwash plate 40 is mounted on the annular flange 38 and removably attached thereto by suitable fasteners such as bolts 42 disposed through apertures n circumferentially spaced arrangement thereabout. The bulkhead 40 has a plurality of fluid flow apertures provided therein in an inner array which apertures are denoted by reference numeral 44; and, bulkhead 40 has an outer array of apertures 46 arranged in circumferentially spaced arrangement surrounding the inner array of apertures 44. The arrangement of the apertures is more clearly illustrated in
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The open end of each shroud tube 48 opposite the bulkhead 40 has an annular flange or seal ring 50 attached thereto, for example, as by weldment, such that the flange 50 is sealed about the shroud tube 48.
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The passage 70 has a shaft extending therethrough and through the rotary coupling 74 with an end thereof connected in driving engagement with the drain arm 76. The opposite end of the shaft 94 extends outwardly of the fitting 66 and is connected to a motor drive indicated generally at 96. Upon activation of the motor drive 96, shaft 94 is operative to rotate the arm 76 in the region 72 of the pressure vessel. As shown in
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Operation of the filtering assembly is illustrated in
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The present disclosure thus describes a filtering assembly in which a horizontally arranged pressure vessel includes a plurality of filter media elements disposed circumferentially spaced in an inner array and an outer array surrounding the inner array. A rotatable drain arm is positioned over a rotary fluid coupling connected to a drain outlet such that, upon rotation by a servo motor, the ends of the drain arm are positioned to coincide with apertures through a bulkhead plate in the vessel to communicate with selected filter media elements in the inner array and outer array. The selected filter media elements are connected through the drain arm to a drain to effect backwashing of the selected filter media elements. A shaft through the outlet port is connected to a servo motor and to the drain arm to effect rotation of the drain arm. The filter media elements are disposed in tubular shrouds having one end welded to the vessel bulkhead with a cover plate over the opposite end. Filtered fluid from the filter media elements flows through apertures in the cover plate over the end of the shroud tube to the vessel outlet port. The filter media elements are disposed such that, upon removal of the vessel closure or lid, the filter media elements may be removed from the tubular shrouds for replacement. The filtering assembly of the present disclosure thus provides for backwashing selected filter media elements in an inner array and an outer array while maintaining filtering flow in the remaining filter media elements.
Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the disclosed versions be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
