Patent Application
20150202560
The subject matter disclosed herein relates to filters, and more particularly to reinforced filters that reduce pressure loss.
A gas turbine engine combusts a fuel-air mixture to generate hot combustion gases, which drive rotation of turbine blades in a turbine section. The gas turbine engine may be used to drive an electrical generator or another load. The gas turbine engine intakes air through an air filter, which removes particulates to protect internal components of the gas turbine engine. Unfortunately, existing air filters may be inadequate for certain environmental conditions, such as heavy fog, dust/sand storms, and other harsh conditions. An inadequate air filter may cause operational problems for the turbine, such as, unforeseen shutdown or increased performance degradation. Thus, under such harsh conditions, the installed air filter would require replacement with another more suitable air filter, thereby resulting in waste of the installed air filter.
Some existing air filters are designed with adjacent pleats or pockets, and during use these pockets can contact each other. When the pockets contact each other pressure loss is increased. This is due to the fact that less filter media is available for air passage. Shelves that extend from one pocket surface directly to an opposing pocket surface have been used to help support the pockets, but this approach suffers from the disadvantage that pre-filters cannot be used or nested with the primary filter.
In an aspect of the present invention, a filter bag assembly includes a first filter bag that includes at least two sidewalls of filter material extending from an open end of the first filter bag to a closed end of the first filter bag at which the sidewalls connect to close the first filter bag. Two of the sidewalls of filter material are opposed to each other across the first filter bag and spaced from each other at the open end of the first filter bag. The at least two sidewalls are configured to form a tapered pocket, and the first filter bag includes a plurality of tapered pockets. A substantially rigid mesh is in contact with the first filter bag. The substantially rigid mesh is configured in a substantially V-shape and located near the open end of the first filter bag. The substantially rigid mesh is configured to maintain a shape of the tapered pockets and reduce filter pressure loss during use of the filter bag assembly.
In another aspect of the present invention, a filter bag assembly has a primary filter bag that includes at least two sidewalls of filter material extending from an open end of the primary filter bag to a closed end of the primary filter bag at which the sidewalls connect to close the primary filter bag. Two of the sidewalls of filter material are opposed to each other across the primary filter bag and are spaced from each other at the open end of the primary filter bag. Two sidewalls are configured to form a tapered pocket, and the primary filter bag includes a plurality of tapered pockets. A substantially rigid mesh is in contact with the primary filter bag. The substantially rigid mesh is configured in a substantially V-shape and located near the open end of the primary filter bag. The substantially rigid mesh is configured to avoid contact between adjacent tapered pockets and reduce filter pressure loss during use of the filter bag assembly.
One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present invention, the articles “a”, “an” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
The filters 11 may be any suitable type, such as bag filters or mini-pleat filters for example. Additionally, the filters 11 may also be any suitable size. For example, in some embodiments, the filter height 38 and width 40 may be approximate 600 mm, the filter depth 42 may be approximately 400 to 800 millimeters, and each filter 11 may weigh between about 2 to about 15 kilograms. Additionally, in some embodiments, the filter cells 30 and/or the filter frame 22 may provide suitable drainage for moisture, which may collect on the outside of the filter 11. Also included in the filter frame 22 are several fasteners or latches 48, which hold the filters 11 within the frame and provide sufficient compression to the sealing flange 44 to provide the airtight seal between the filter 11 and the sealing face 34.
A substantially rigid mesh 630 is placed in contact with the filter bag 600. The mesh 630 is configured in a substantially V-shape and located near the open end 641 of the filter bag 600. The rigid mesh 630 is configured to maintain a tapered shape of the tapered pockets 601-604 and reduce filter pressure loss during use of the filter bag assembly. The mesh 630 may be comprised of a steel or galvanized steel wire mesh having openings of about ¼inch to about 1 inch in size. The wire may have a diameter from about 0.06 inches to about 0.25 inches and the mesh 630 may have an open area of about 75% to about 95%. It is to be understood that other materials (e.g., metal, metal alloys, plastics, natural materials, etc.) may be employed to fabricate the mesh 630, and that wire and open areas of other sizes resulting in different percentages of open areas may be sued without departing from the spirit and scope of the present invention. As one example only, a plastic mesh may have “wire” that is rectangular in profile (or cross-section). An important feature is that an open area of at least 50% or greater is used to reduce filter pressure loss during use of the filter bag. Open areas of less than 50% can be used, but will result in greater filter pressure loss when compared with more open area meshes. In addition, the mesh should be designed to have enough rigidity to maintain the substantially V-shape during use of the filter 600, and in so doing the wire diameter should be chosen accordingly.
The rigid mesh 630 is also configured to cover only a portion of the tapered pockets, with a remainder of the tapered pockets having no rigid mesh. This feature will further decrease filter pressure loss. For example, the rigid mesh 630 could be configured to cover about 50% of the tapered pockets (as shown in
The substantially rigid mesh 630 may be attached to outer portions (e.g., the downstream side) of adjacent tapered pockets (as shown), or the mesh 630 may be attached to the frame 644 of the filter bag 600. The mesh 630 could be held in place by friction as the filter media 625 will tend to partially envelope the wire mesh, or the mesh could be sewn, tied or adhesively connected to the filter media 625. The mesh 630 could also be tied or clamped to the frame 644, by any suitable fastener (e.g., clamps, wire or plastic ties, string or twine, etc.). In additional embodiments, the mesh 630 could be embedded within the filter media/material 625 or attached to the upstream side of the tapered pockets.
The second filter bag 700 (or pre-filter) includes at least two sidewalls 721, 722 of filter material 725 extending from an open end 741 of the second filter bag 700 to a closed end 742 of the second filter bag at which the sidewalls connect to close the second filter bag. The sidewalls are configured to form a tapered pocket, and the second filter bag includes a plurality of tapered pockets 701, 702, 703, 704. The second filter bag 700 (i.e., pre-filter) is configured to nest substantially within the first filter bag 600 (i.e., main filter). The pre-filter 700 can be removed and cleaned or exchanged with a new pre-filter without taking the gas turbine off-line, as the main filter 600 continues to filter the incoming air. The rigid mesh 630 maintains the desired tapered shape of both the main filter 600 and the pre-filter 700.
The mesh 833 may also include one or more mesh reinforcement member 851, 852 configured to support the substantially rigid mesh 833. The reinforcement member 851 or 852 is designed to be substantially rigid to support the mesh 833 so the mesh 833 will maintain its substantially V-shape. The reinforcement member 851 may be a rigid wire, rigid pole or any member capable of resisting collapse of the V-shaped mesh 833. The reinforcement member 852 may be rigid member having a cross-sectional I-shape for further strength and rigidity, and the member 852 could be comprised of metal, plastic, natural materials or mixtures thereof. Single or multiple reinforcement members could be used for each individual V-shaped mesh section.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
