Patent Description:
In <CIT> there is disclosed a filter unit as it is defined in the precharacterizing portion of claim <NUM>.

Many hydrocarbon refining processes utilize catalytic reactors to add value to lower quality feedstocks. Catalytic reactors are large vessels filled with catalyst particles arranged in trays, through which the feedstock oil flows. By adding steam or hydrogen, the oil can be improved to more valuable products such as fuels and lubricating oil. The catalyst reactor must be protected by filtration to optimize the life of the catalyst particles and minimize differential pressure across the reactor.

A need exists for still further improvements in connection with refinery protection filtration. Improved performance is desired by increasing solids loading capacity, decreasing specific flowrate during filtration, and improving backwash effectiveness. Any improvements are preferably capable of retrofitting existing filter systems, in addition to being used in new installation.

Generally, filter units of this type include two operating modes, namely, (i) filtration mode and (ii) backwash mode. In the filtration mode, dirty process liquid flows through the filter housing entrance or inlet and to the outside of the filter element sticks. The fluid passes through the filter media, leaving any separated solids to accumulate on the exterior of the stick surface. Clean fluid then passes through the interior of each filter stick and ultimately through a flange into the outlet portion of the filter housing and onward. The flange serves as a separation between dirty and clean portions of the filter housing to prevent cross-contamination.

As solids accumulate on the filter elements or filter sticks during filtration mode, differential pressure begins to rise between the inlet and outlet sides of the filter housing. Once this differential pressure reaches a terminal value, the filter element is regenerated by backwashing. During a backwash cycle, the flow is reversed across the filter housing. Clean fluid is supplied under pressure to serve as the backwashing medium. The clean backwash fluid flows through the element flange into each of the individual filter elements or filter sticks, flowing down each stick and then through. The backwash flow is intended to dislodge the accumulated solids on the exterior of each stick and then flush them away, thus regenerating the filter element. A typical backwash cycle takes <NUM>-<NUM> seconds and turns the volume of fluid in the housing over several times.

A need exists for an improved geometric arrangement to ensure a consistent and maximized spacing between the filter sticks, which will improve flow distribution and filter cake formation during filtration mode.

Poor backwashing recovery over certain areas of each filter stick was observed, resulting in an eventual loss of effective filter area. This reduction of effective filter area is sometimes referred to as "seasoning" of the filter element and typically occurred early in the use of new filter elements. The reduction in operational cycle time between backwashes ultimately stabilized at a final, reduced cycle time, and one area for improvement was identified to reduce or eliminate element "seasoning".

A need exists for an improved arrangement that provides at least one or more of the above-described features, as well as still other features and benefits.

This invention relates to a new filter unit, and particularly a filter unit that increases solids loading capacity, decreases specific flowrate during filtration, and improves backwash effectiveness.

A preferred embodiment of a filter unit for removing matter from an associated process stream includes a housing having a first, inlet end and a second, outlet end spaced from one another along a longitudinal axis. Plural elongated, spaced filter elements are received in the housing and extend between the inlet and outlet ends thereof and are laterally spaced from one another to enhance matter removal from the associated process stream. A single piece flow shaping nozzle module is located at the outlet end of the housing, and includes plural openings, one for each of the plural filter elements, for enhancing more uniform flow over the filter elements. The plural openings of the single piece flow shaping nozzle module including enlarged dimension portions adjacent a first face thereof, smaller dimension portions adjacent a second face thereof, and smoothly contoured transition regions interconnecting each enlarged dimension portion with an associated smaller dimension portion in an intermediate region of the single piece flow shaping nozzle module.

In one version, the enlarged dimension portions of the openings in the single piece flow shaping nozzle module merge into an arcuate surface on the first face of the single piece flow shaping nozzle module.

The arcuate surface may be a single arcuate shape extending over a major portion of the first face of the single piece flow shaping nozzle module, and may be concave, e.g., hemispherical.

A dividing member extending diametrically across the single piece flow shaping nozzle module may include an airfoil cross-sectional shape.

In another version, a central portion of the first face of the single piece flow shaping nozzle module extends outwardly a greater dimension than a peripheral portion thereof, and a sloping region interconnecting the central portion with the peripheral portion.

A central opening in the central portion may be circumscribed by alternating peaks and valleys.

The second face of the single piece flow shaping nozzle module is preferably planar.

In still another embodiment of the single piece flow shaping nozzle module, each opening in the first face is circumscribed by alternating peaks and valleys.

A ninety-degree passage secured adjacent the outlet preferably includes a flow diverting member therein that improves flow and pressure distribution into the single piece flow shaping nozzle module during reverse flow through the filter unit.

The flow diverting member is preferably located in the ninety-degree passage at an elbow thereof.

An increased number of filter elements (from <NUM> filter elements to <NUM> filter elements) still has similar overall dimensions to the existing commercial filter unit and thus can be fitted into existing filter systems.

The increased number of filter elements results in an approximately <NUM>% increase in surface area by increasing filter element sticks to <NUM>. This increase in surface area can directly increase the throughput capacity of an existing filter installation by element replacement.

Optimizing flow distribution also reduces hydraulic flow loss across the element.

Another advantage resides in maximizing element solids capacity through optimized filter element stick spacing.

Yet another improvement relates to reducing operating costs both through potential reduction in initial equipment installation, as well as reduction of backwash waste stream.

Still another benefit is associated with a nozzle entrance module which optimizes backwash efficiency by reducing flow entrance effects into the sticks or filter elements during reverse flow, which will recover more surface area during backwash by minimizing entrance effects, and improving flow and pressure distribution inside the filter sticks during backwash cycle operation. Changes were made to address flow separation and recirculation in the first several inches of each stick directly below the flange caused at least in part by a high-velocity entrance region (<NUM> inch ≙ <NUM>,<NUM>).

A new flow-shaping nozzle module is preferably a separate piece or component that is installed on the flange and utilizes an optimized geometry design. As the fluid mechanics governing entrance effects are dependent upon both tube diameter and geometry as well as a fluid entrance number that is based on Reynolds number (fluid parameters including density, dynamic viscosity and flow velocity), custom flow-shaping nozzle modules can be designed for different applications, and optimized for different fluids and process conditions. Preferably, the flow-shaping nozzle module bolts onto the element assembly so that it is possible to change out easily and tailor the nozzle module to specific process conditions.

Benefits and advantages of the present invention will become more apparent from reading and understanding the following detailed description.

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of one or more embodiments of the present invention as defined by the claims and their equivalents. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope of the present invention as it is defined by the appended claims. Various exemplary embodiments of the present invention are not limited to the specific details of different embodiments and should be construed as including all changes and/or equivalents or substitutes included in the ideas and technological scope of the appended claims. In describing the drawings, where possible similar reference numerals are used for similar elements.

The terms "include" or "may include" used in the present disclosure indicate the presence of disclosed corresponding functions, operations, elements, and the like, and do not limit additional one or more functions, operations, elements, and the like. In addition, it should be understood that the terms "include", "including", "have" or "having" used in the present disclosure are to indicate the presence of components, features, numbers, steps, operations, elements, parts, or a combination thereof described in the specification, and do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, parts, or a combination thereof.

The terms "or" or "at least one of A or/and B" used in the present disclosure include any and all combinations of words enumerated with them. For example, "A or B" or "at least one of A or/and B" mean including A, including B, or including both A and B.

Although the terms such as "first" and "second" used in the present disclosure may modify various elements of the different exemplary embodiments, these terms do not limit the corresponding elements. For example, these terms do not limit an order and/or importance of the corresponding elements, nor do these terms preclude additional elements (e.g., second, third, etc.) The terms may be used to distinguish one element from another element. For example, a first mechanical device and a second mechanical device all indicate mechanical devices and may indicate different types of mechanical devices or the same type of mechanical device. For example, a first element may be named a second element without departing from the scope of the various exemplary embodiments of the present invention, and similarly, a second element may be named a first element.

It will be understood that, when an element is mentioned as being "connected" or "coupled" to another element, the element may be directly connected or coupled to another element, and there may be an intervening element between the element and another element. To the contrary, it will be understood that, when an element is mentioned as being "directly connected" or "directly coupled" to another element, there is no intervening element between the element and another element.

The terms used in the various exemplary embodiments of the present invention are for the purpose of describing specific exemplary embodiments only and are not intended to limit various exemplary embodiments of the present invention. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise.

All of the terms used herein including technical or scientific terms have the same meanings as those generally understood by an ordinary skilled person in the related art unless they are defined otherwise. The terms defined in a generally used dictionary should be interpreted as having the same meanings as the contextual meanings of the relevant technology and should not be interpreted as having inconsistent or exaggerated meanings unless they are clearly defined in the various exemplary embodiments.

Turning initially to <FIG> and <FIG>, there is shown a filter assembly or filter unit <NUM> that includes a housing <NUM>. The housing <NUM> includes a first or inlet port <NUM> adjacent a first end of the housing <NUM> and a second or outlet port <NUM> adjacent a second end of the housing. Dirty process fluid, i.e., liquid, is introduced into the filter housing <NUM> through inlet <NUM> and exits the housing post-filtration at outlet <NUM>. Defined between the inlet <NUM> and outlet <NUM> is a hollow chamber or cavity <NUM> that receives multiple filter elements or filter element sticks <NUM>. Although the commercial embodiment shown and described in commonly owned <CIT> included twenty-eight filter element sticks the present invention increases this number to thirty-one filter element sticks as will be described further below.

Each filter element stick <NUM> is an elongated hollow structure such as a metal rod that receives the flow around the outer perimeter thereof. The fluid passes through the filter media of the filter element sticks <NUM> whereby separated solids that cannot pass through the filter media accumulate on the exterior surface of the filter element sticks. Clean fluid passes through and continues through the interior of each filter element stick <NUM> and exits the cavity <NUM> passing through a disk-shaped flange <NUM>. More particularly, the disk-shaped flange <NUM> preferably receives a coupling end <NUM> of each of the filter stick elements <NUM> and thus the disk-shaped flange <NUM> includes a same number of openings <NUM> as there are filter element sticks <NUM> so that each stick is secured to a separate opening (<FIG>). The disk-shaped flange <NUM> is provided with internal threads in each of the openings <NUM>. More particular details of one preferred fastening arrangement is detailed in the '<NUM> patent, although other fastening arrangements such as welding are also contemplated. A flange or plate <NUM> is received over and secures the disk-shaped flange <NUM> to an enlarged radial shoulder <NUM> of the housing with circumferentially spaced fasteners <NUM>. As also illustrated in <FIG>, lower ends <NUM> of the filter element sticks <NUM> are received in openings <NUM> of a support member <NUM>. Further, the support member <NUM> receives one end of elongated coupling rods <NUM> that extend parallel to the filter element sticks <NUM> and have their opposite ends threadedly received in the disk-shaped flange <NUM>. Still further, a plate <NUM> includes openings <NUM> to receive threaded ends of the coupling rods <NUM> threaded into fastener members or nuts <NUM>, and also includes openings <NUM> that are concentric with and have the same diameter as the bores formed in the coupling heads <NUM> at the outlet end of the filter element sticks <NUM> and concentrically aligned with the openings <NUM> in the disk-shaped flange <NUM>. The plate <NUM> acts as a retainer to keep the filter element sticks from leaving flange <NUM>.

Turning to <FIG>, a new arrangement of the filter unit includes an increased number of filter element sticks <NUM> (similar to filter element sticks <NUM> of the prior arrangement and reference numerals are identified in the "<NUM>" series for ease of reference and understanding with respect to those components previously identified in the "<NUM>" series). The elongated filter element sticks <NUM> are closed at first or lower ends <NUM> and second or upper ends are received in openings <NUM> in the disk-shaped flange <NUM>. A primary difference between those features illustrated in <FIG> and the prior art arrangement of <FIG> and <FIG> relates to the number of filter element sticks <NUM>. As noted previously, the number of filter element sticks <NUM> is increased to correspondingly increase the total surface area of the filter arrangement by approximately <NUM>%. This increase of surface area directly increases the throughput capacity of existing filter installations where the filter element sticks <NUM> and disk-shaped flange <NUM> are used to replace the existing filter element sticks <NUM> and flange arrangement <NUM>.

As more particularly illustrated in a first embodiment shown in <FIG>, flow-shaping nozzle module <NUM> includes openings <NUM> to receive fasteners such as bolts (not shown) to secure the flow shaping nozzle module to the disk-shaped flange <NUM>. The flow shaping nozzle module also includes openings <NUM> that are modified to provide the desired flow shaping features not present in the prior arrangements. More particularly, as particularly evident in <FIG>, the flow shaping features associated with the openings <NUM> control the fluid flow during backwash by providing a contoured arrangement that minimizes entrance effects and improves flow and pressure distribution inside the filter element sticks <NUM> during backwash. The flow shaping nozzle module <NUM> is preferably a separate component (so that it can be advantageously substituted or retrofit into existing filter units) installed on the flange <NUM> and the flow shaping nozzle module uses an optimized geometry to enhance flow distribution that reduces hydraulic flow losses across the filter element and improves backwash effectiveness. This design minimizes entrance effects and improves flow and pressure distribution inside the filter sticks during backwash cycle operation. It was observed that prior arrangements had a pronounced entrance effect where the high velocity in the entrance region caused flow separation and recirculation in the first several inches or upper portion of each stick directly below the flange (<NUM> inch ≙ <NUM>,<NUM>). These effects resulted in poor backwashing recovery over this area of each filter stick, ultimately resulting in an eventual loss of effective filter area (sometimes referred to as "seasoning" of the filter element that occurred during early use of new filter elements). As a result of this reduction in effective filter area, a corresponding reduction in operational cycle time between backwashes was exhibited, ultimately stabilizing at a final, reduced cycle time. By including the flow shaping nozzle module <NUM>, improved flow characteristics particularly in the entrance region (i.e., the first several inches of each stick directly below the flange <NUM>) are achieved to provide more effective backwashing.

As evident in <FIG>, the flow shaping nozzle module <NUM> is preferably a separate component that is installed on top of the disk-shaped flange <NUM> (<FIG>). The geometry of the flow shaping nozzle module <NUM> can adopt a variety of configurations since entrance effects during backwash are dependent on both the tube diameter, geometry, and fluid entrance number based on Reynolds number (fluid parameters including density, dynamic viscosity, and flow viscosity). Since the flow shaping nozzle module <NUM> is fastened (e.g., bolted) to the flange <NUM>, the flow shaping nozzle module can be easily changed out as deemed necessary.

As shown in <FIG>, <FIG>, one preferred embodiment includes openings <NUM> that have enlarged dimension portions 264A adjacent a first or upper face <NUM> of the flow shaping nozzle module <NUM> and the opening reduces in cross-sectional dimension, i.e., tapers toward a smaller dimension portion 264B adjacent a second face <NUM> of the flow shaping nozzle module. Further, alternating peaks 264C and valleys 264D surround a perimeter of each opening <NUM> at the enlarged dimension portion 264A adjacent the upper face <NUM> of the flow shaping nozzle module <NUM>. The peaks 264C and valleys 264D include smooth transitions that optimize the flow through the flow shaping nozzle module <NUM> and ultimately into the upper ends of the filter element sticks <NUM> during backwash.

A second embodiment of a flow shaping nozzle module is shown in <FIG>, and for purposes of brevity and understanding, reference numerals in the "<NUM>" series are used in connection with this alternate embodiment of flow shaping nozzle module <NUM>. The flow shaping nozzle module <NUM> is again preferably a separate component that is installed on top of the disk-shaped flange <NUM> (<FIG>). Generally, the openings <NUM> include enlarged dimension portions 364A adjacent the upper, first face <NUM> of the flow shaping nozzle module <NUM> while smaller dimension portions 364B are provided adjacent the second, lower face <NUM> of the flow shaping nozzle module. To further smooth the transition of flow characteristics during backwash through the flow shaping nozzle module <NUM>, this embodiment includes an arcuate surface, particularly concave (hemispherical) surface <NUM>, and as a result of incorporating the concave surface, the openings <NUM> at the backwash entrance regions 364A are elongated or stretched to form partial ellipsoids. These structural characteristics of the flow shaping nozzle module <NUM> result in a more even flow distribution as the backwash flow enters into the individual filter element sticks. In addition, a handle <NUM> extends diametrically across the first face <NUM> of the flow shaping nozzle module <NUM> to aid in installation and removal of the flow shaping nozzle module. As best seen in <FIG>, the dividing member <NUM> preferably has an airfoil cross-sectional shape to facilitate smooth fluid flow therearound during the backwash process.

A third embodiment of a flow shaping nozzle module <NUM> is shown in <FIG>. Here, the flow shaping nozzle module <NUM> has an arcuate shape <NUM> that extends outwardly from the first, upper face <NUM>. More particularly, the arcuate shape <NUM> includes a central portion of the first face <NUM> that extends outwardly a greater dimension than a peripheral portion thereof, and a sloping region interconnecting the central portion with the peripheral portion on the first face. A central opening <NUM> in the central portion is circumscribed by alternating peaks <NUM> and valleys <NUM>. As a result of the outwardly extending central portion <NUM>, the entrance regions 464A and the openings <NUM> have elongated or stretched configurations that communicate with exit regions 464B located adjacent the second, lower face of the flow shaping nozzle module. On the other hand, the second or lower face <NUM> of the flow shaping nozzle module <NUM> is planar, allowing the flow shaping nozzle module to abut or mate with the flange <NUM>.

Figures <NUM> - <NUM> particularly illustrate a flow diverting member <NUM> that can be used as a separate feature or in combination with one of the flow shaping nozzle modules disclosed above. The flow diverting member <NUM> is dimensioned for receipt in the outlet passage <NUM> that forms the outlet of the filter unit. Particularly, the flow diverting member <NUM> is located in the <NUM>° passage portion i.e., preferably at the elbow <NUM> of the passage <NUM>. In a preferred form, the flow diverting member <NUM> includes a central vertical member <NUM> that divides the passage in half, and two or more lateral members <NUM> that extend outwardly from opposite faces of the vertical member act as vanes to distribute flow. Each of the vertical member <NUM> and lateral members <NUM> are smoothly contoured in order to redirect and smooth fluid flow through the elbow of the passage <NUM> so that during the backwash process, backwash flow exits the passage more uniformly across the cross-section of the passage before entering into a flow shaping nozzle module. The flow diverting member <NUM> is preferably a separate component that can be used to retrofit existing filter units, as well as advantageously used with one of the flow shaping nozzle modules described above.

In summary, the present filter unit features a <NUM>-stick design with, for example, an <NUM>" flange design. It has similar overall dimensions to existing filter units such as shown in <FIG> and thus can be fitted into existing filter systems using <NUM>" element designs.

The theory of operation for flanged filter elements includes two operating modes: A) filtration mode; and B) backwash mode. In filtration mode, dirty process liquid is flowed through the filter housing entrance and to the outside of the filter element sticks. The fluid passes through the filter media, leaving any separated solids to accumulate on the exterior of the stick surface. Clean fluid then passes through the interior of each filter stick and ultimately through a flange into the outlet portion of the filter housing and onward. The flange serves as a separation between dirty and clean portions of the filter housing to prevent cross-contamination.

As solids accumulate on the filter sticks during filtration mode, differential pressure begins to rise between the inlet and outlet sides of the filter housing. Once this differential pressure reaches a terminal value, the filter element is regenerated by backwashing. During a backwash cycle, the flow is reversed across the filter housing. Clean fluid is supplied under pressure to serve as the backwashing medium. The clean backwash fluid flows through the element flange into each of the individual sticks, flowing down each stick and then through. The backwash flow is intended to dislodge the accumulated solids on the exterior of each stick and then flush them away, thus regenerating the filter element. A typical backwash cycle takes <NUM>-<NUM> seconds and turns the volume of fluid in the housing over several times.

The present filter unit arranges a quantity of <NUM> of <NUM>" diameter filter sticks into an optimized array. The geometric arrangement ensures a consistent and maximized spacing between the filter sticks, which will improve flow distribution and filter cake formation during filtration mode. The addition of three more elements increases the surface area of the element by <NUM><NUM>%. This increase of surface area can directly increase the throughput capacity of an existing filter installation by element replacement, and it can also improve competitive position of new systems. Optimized flow distribution will also reduce hydraulic flow loss across the element.

A unique feature of the present filter unit is the use of a flow-shaping nozzle module to optimize the flow into the element during backwash. Flow behavior in prior arrangements was similar to venturi-orifice flow, with a pronounced entrance effect region. This high-velocity entrance region caused flow separation and recirculation in the first several inches of each stick directly below the flange (<NUM> inch ≙ <NUM>,<NUM>). These effects resulted in poor backwashing recovery over this area of each filter stick, resulting in an eventual loss of effective filter area. This observed reduction of effective filter area was referred to as "seasoning" of the filter element and typically occurred early in the use of new elements. It was denoted by a reduction in operational cycle time between backwashes, ultimately stabilizing at a final, reduced cycle time. It is a goal of the present unit to reduce or eliminate element "seasoning" by minimizing entrance effects and improving flow and pressure distribution inside the filter sticks during backwash cycle operation.

The flow-shaping nozzle module is a separate piece that is installed on the flange and utilizes an optimized geometry design, although it is contemplated that the flow-shaping nozzle module and flange could be formed as a single component. As the fluid mechanics governing entrance effects are dependent upon both tube diameter and geometry as well as a fluid entrance number that is based on Reynolds number (fluid parameters including density, dynamic viscosity and flow velocity), it is believed that custom flow-shaping nozzle modules can be designed for different applications, optimized for different fluids and process conditions. As the module bolts onto the element assembly, it is possible to change out easily.

Claim 1:
A filter unit for removing matter from an associated process stream, the filter unit comprising:
a housing (<NUM>) having a first, inlet end and a second, outlet end spaced from one another along a longitudinal axis; and
plural elongated, spaced filter elements (<NUM>) received in the housing and extending between the inlet and outlet ends thereof and laterally spaced from one another to enhance matter removal from the associated process stream;
characterized in that the filter unit further comprises:
a single piece flow shaping nozzle module (<NUM>; <NUM>; <NUM>) located at one of the inlet and outlet ends of the housing, the single piece flow shaping nozzle module including plural openings (<NUM>; <NUM>; <NUM>), one for each of the plural filter elements (<NUM>), for enhancing more uniform flow over the filter elements, the plural openings of the single piece flow shaping nozzle module including enlarged dimension portions (264A; 364A; 464A) adjacent a first face (<NUM>; <NUM>; <NUM>) thereof, smaller dimension portions adjacent a second face (<NUM>; <NUM>; <NUM>) thereof, and smoothly contoured transition regions interconnecting each enlarged dimension portion with an associated smaller dimension portion in an intermediate region of the single piece flow shaping nozzle module, wherein each of the plural filter elements (<NUM>) is received in one of the plural openings (<NUM>; <NUM>; <NUM>).