Patent Description:
Many industries encounter particulate matter suspended in the atmosphere. In some industries, this particulate matter is a valuable product (for example, starch), and it would be beneficial if the suspended particulate matter could be recovered and reintroduced into the process. For other industries (for example, metal or wood working), it may be desirable to remove the particulate matter from the air in order to provide a clear working environment.

Some systems for cleaning an air or other gas streams laden with particulate matter include filter bags (sometimes referred to as socks) located in a housing. The filter bags are typically constructed of filter media, e.g., fabric, pleated paper, etc. The gas stream contaminated with particulate matter is typically passed through the housing so that the particulate matter is captured and retained by one or more filter bags.

Air filter systems typically include a clean air chamber and a dirty air chamber. The two chambers are separated by a structure that is commonly referred to as a tubesheet. The tubesheet has a number of openings so that air can pass between the clean and dirty air chambers. The filter bags are positioned over the openings so that particulate-laden air (dirty air) introduced into the dirty air chamber must pass through a filter bag to move into the clean air chamber. The particulate matter in the dirty air collects on the filter bags as the air moves through the filter bags.

From the clean air chamber, the cleaned air is exhausted into the environment, or recirculated for other uses. See, for example, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>), <CIT>, <CIT>. ), <CIT>, and <CIT>).

As the filter bags capture particulate matter, flow through the system is inhibited and periodic cleaning of the filter bags can be performed to increase air flow through the system. Cleaning can be accomplished by periodically pulsing a brief jet of pressurized air into the interior of the filter bag to reverse the air flow through the filter bag, causing the collected particulate matter to be driven off of the filter bag. The pressurized air may be directed into pulse collectors as described in, e.g., <CIT>, <CIT>, <CIT>, <CIT>, <CIT>), <CIT>, and US Patent Application Publication <CIT>. <CIT> and <CIT> disclose filters with filter bags engaged to a tubesheet.

An air filter system according to the invention is disclosed in any one of claims <NUM>-<NUM>, a use of the filter system according to the invention is disclosed in claim <NUM>, and a method of sealing a filter bag over an aperture in a tubesheet is disclosed in any one of claims <NUM>-<NUM>.

As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" or "the" component may include one or more of the components and equivalents thereof known to those skilled in the art. Further, the term "and/or" means one or all of the listed elements or a combination of any two or more of the listed elements.

It is noted that the term "comprises" and variations thereof do not have a limiting meaning where these terms appear in the accompanying description. Moreover, "a," "an," "the," "at least one," and "one or more" are used interchangeably herein.

The above summary is not intended to describe each embodiment or every implementation of the air filter systems and methods described herein. Rather, a more complete understanding of the invention will become apparent and appreciated by reference to the following Description of Illustrative Embodiments and claims in view of the accompanying figures of the drawing.

In the following description of illustrative embodiments, reference is made to the accompanying figures of the drawing which form a part hereof, and in which are shown, by way of illustration, specific embodiments. It is to be understood that other embodiments may be used and structural changes may be made without departing from the scope of the present invention.

Referring to <FIG>, one illustrative embodiment of an air filter system is depicted generally at <NUM>. The air filter system depicted in <FIG> is generally in the shape of a box and includes an upper wall panel <NUM>, and two pairs of opposite side wall panels <NUM> (one of which is visible in <FIG>). The air filter system <NUM> includes a dirty air conduit <NUM> for receiving dirty or contaminated air (i.e., air with particulate matter therein) into the filter system <NUM>. A clean air conduit <NUM> (see, e.g., <FIG>) may be provided for removing clean or filtered air from the filter system <NUM>. The air filter system <NUM> includes covers <NUM> closing access ports in the access panel <NUM> of the air filter system <NUM>.

The air filter system may also include a hopper <NUM> to collect particulate matter separated from the dirty air stream as described herein. The hopper <NUM> may include sloped walls to facilitate collection of the particulate matter and may, in some embodiments, include a driven auger or other mechanism for removing the collected particulate matter.

The air filter system of <FIG> is depicted in a side elevation in <FIG> and a top plan view in <FIG>. The air filter system <NUM>, as seen in <FIG>, includes connectors <NUM> in fluid communication with pulse generators (not depicted in <FIG>) as part of a pulse-jet cleaning system, with the pulse generators configured to direct a pulse of air into the filter bags as described herein.

With reference to <FIG> and <FIG>, the depicted air filter system <NUM> includes filter bag assemblies including filter bags <NUM> and flange assemblies <NUM> in a dirty air chamber <NUM> that is separated from a clean air chamber <NUM> by a tubesheet <NUM>. <FIG> is a cross-sectional view of the air filter system <NUM> taken along line 4A-4A in <FIG> and shows the interior of the air filter system <NUM> (with the filter bags <NUM> located therein being intact such that the support structure within the filter bags <NUM> is obscured from view). <FIG> is a cross-sectional view of the air filter system <NUM> taken along line <NUM>-<NUM> in <FIG> (with the cross-sectional view depicting the interior volume of the filter bags <NUM> such that a portion of the support structure within the filter bags <NUM> is depicted). The filter bag assemblies are mounted on filter guides <NUM> located in the dirty air chamber <NUM>. In the depicted illustrative embodiment, the filter guides <NUM> extend across the dirty air chamber <NUM> from the tubesheet <NUM> to the access panel <NUM> of the air filter system.

The filter bags used in the air filter systems described herein may be constructed of any suitable filter media in view of the particulate matter to be collected, airflow requirements, strength requirements, etc. Suitable filter bags may be constructed of filter media that includes one or more of polyester, polypropylene, aramid, polyester/polytetrafluoroethylene material in both woven and/or nonwoven constructions, etc..

In one or more embodiments, the filter bags used in the filter bag assemblies described herein may be distinguished from filter cartridges based on their response to compression forces directed between the filter bag opening and the second end of the filter bag, i.e., the end of the bag located opposite the bag opening. In the absence of any extraneous support (such as, e.g., the internal cages described herein), filter bags used in the filter bag assemblies described herein would, in one or more embodiments, deform under a compressive force of <NUM> Newtons (approx. <NUM> pound-force) directed along a line extending through the bag opening to the distal/closed end of the filter bag (e.g., along the cage axis <NUM> depicted in <FIG>). In addition to deforming, one or more embodiments of the filter bags used in the filter bag assemblies described herein, transmit essentially none of such a compressive force. A filter cartridge would, in contrast, not significantly deform and would transmit most, if not all, of such a compressive force. The flexibility that is the source of the inability of the filter bags used in the filter bag assemblies and air filter systems described herein to transmit compressive forces is, however, the source of the filter bags' ability to rapidly accelerate (sometimes referred to as "snap") outward to remove particulate matter collected on the exterior of the filter media in response to a cleaning pulse.

At the tubesheet end, each of the filter bag assemblies includes a flange assembly <NUM>. The flange assembly <NUM> includes an interior face <NUM> facing the dirty air chamber <NUM> and a tubesheet face that seals against the dirty air chamber side of the tubesheet <NUM>. Each of the flange assemblies <NUM> surrounds an aperture in the tubesheet <NUM> through which clean air can pass from the interior of a filter bag assembly into the clean air chamber and through which a pulse of air can pass into the interior of a filter bag during a pulse cleaning event.

Although the flange assemblies <NUM> on each of the filter bag assemblies will be described in more detail herein, the depicted illustrative embodiment of flange assemblies <NUM> seen in <FIG> includes a base <NUM> including the tubesheet face of the flange assembly <NUM> and a clamp <NUM> configured to attach to the base <NUM> on the interior face of the flange assembly <NUM>. In such an embodiment, the clean air outlet extends through the base <NUM> and the clamp <NUM>, with the bag opening of the filter bag <NUM> being retained between the clamp <NUM> and the base <NUM> on the interior face of the flange assembly <NUM>.

The illustrative embodiment of air filter system <NUM> as depicted in <FIG> also includes pulse generators <NUM> located in the clean air chamber <NUM>. The pulse generators <NUM> are configured to deliver pulses of air into the interior volumes of the filter bags <NUM> to drive particulate matter that has accumulated on the filter bags <NUM> during use of the filter bags, with the dislodged particulate matter preferably falling into the hopper <NUM> located below the filter bags <NUM>. In one or more embodiments, the pulse generators <NUM> may be described as having elongated shapes that extend along pulse generator axes <NUM> as seen in, e.g., <FIG>. Pressurized air (or any other suitable gas) is delivered to the pulse generators through connectors <NUM> that, in the depicted embodiment, extend outside of the clean air chamber <NUM> for connection to a pulse cleaning system including one or more sources of pressurized gas (e.g., air), valves and a control system. Illustrative embodiments of pulse cleaning systems may be found in, e.g., <CIT>, <CIT>, <CIT>, <CIT>, <CIT>), and <CIT>.

Also depicted in connection with the illustrative embodiment of air filter system <NUM> are pulse collectors <NUM> which, as will be described herein, may be attached to the flange assemblies <NUM> of the filter bag assemblies. In other embodiments, the pulse collectors <NUM> may be attached to the tubesheet <NUM>. Regardless of the structure to which they are attached, the pulse collectors <NUM> are configured to direct pulsed air emitted from the pulse generators <NUM> into the interior volumes of the filter bags <NUM> during the pulse cleaning process.

<FIG> are cross-sectional views taken along line 4B-4B in <FIG>, with <FIG> being taken when the air filter system <NUM> is either not in use or is being used to filter dirty air being delivered into the dirty air chamber <NUM> through inlet <NUM>. <FIG> depicts the filter bag <NUM> relative to the other structures of the filter bag assembly during a pulse cleaning event when pressurized air (or other gas) is delivered into the interior volume of the filter bag <NUM> as described herein.

<FIG> depicts a portion of the dirty air chamber side of the tubesheet <NUM> with flange assembly <NUM> located thereon. As discussed herein, the depicted illustrative embodiment of flange assembly <NUM> includes a base <NUM> and a clamp <NUM>, with the bag opening of the filter bag <NUM> being retained between the clamp <NUM> and the base <NUM> such that air can enter the interior volume of filter bag <NUM> only by passing through the filter media used to construct filter bag <NUM> or by passing through the clean air outlet <NUM> of the flange assembly <NUM>.

The filter bag assembly as seen in <FIG> includes a cage used to hold the filter bag <NUM> in a triangular shape (with the cage being seen in the cross-sectional view of <FIG>). In the depicted illustrative embodiment, the cage includes a first cage end attached to the flange assembly <NUM>, with the cage extending away from the flange assembly <NUM> over a cage length along a cage axis <NUM> to a second cage end distal from the flange assembly <NUM>. In the depicted illustrative embodiment, the second cage is located proximate the access panel <NUM> of the air filter system <NUM>.

In the depicted illustrative embodiment of the filter bag assembly, the cage includes a plurality of struts that extend away from the interior face of the flange assembly <NUM> towards the second cage end proximate the access panel <NUM> of the air filter system <NUM>. The plurality of struts define a triangular shape such that, in each cross-section taken in a plane transverse to the cage axis <NUM> over a majority of the length of the cage, the plurality of struts define a triangle having a top vertex and a pair of bottom vertices opposite the top vertex.

In the depicted illustrative embodiment, the cage includes a top strut <NUM> and a pair of bottom struts <NUM> and <NUM>. The top strut <NUM> defines a top vertex of the triangles defined by the plurality of struts, while the pair of bottom struts <NUM> and <NUM> defined the bottom vertices of the triangles defined by the plurality of struts. The depicted illustrative embodiment of the cage also includes a series of braces <NUM> extending from the top strut <NUM> to each of the bottom struts <NUM> and <NUM> to provide additional support to the filter bag <NUM> at selected locations along the length of the cage.

When the cage is located in the filter bag <NUM>, the filter media of the filter bag <NUM> may be described as defining a pair of side surfaces <NUM> and a bottom surface <NUM>. Each of the side surfaces <NUM> includes a top edge proximate the top vertex (as defined by the top strut <NUM>) of each triangle defined by the plurality of struts. Moreover, each side surface <NUM> also includes a bottom edge distal from the top edge of the side surface <NUM>. With reference to <FIG>, the bottom edge of the right side surface <NUM> is defined by the right side bottom vertex (as defined by bottom strut <NUM>) of each triangle defined by the plurality of struts, while the bottom edge of the left side surface <NUM> is defined by the left side bottom vertex (as defined by bottom strut <NUM>) of each triangle defined by the plurality of struts.

Because the filter bags used in the filter bag assemblies of air filter systems as described herein are made of generally flexible filter media, the top edges and bottom edges of the triangular-shaped filter bags may not be particularly distinct, i.e., the edges may not form a single line. It will, however, be understood that the edges may have a width around which the filter media extends when moving from the side surfaces <NUM> to the bottom surface <NUM> around the bottom struts <NUM> and <NUM> and/or when moving from one side surface <NUM> to the opposite side surface over the top strut <NUM>. Regardless of that lack of distinctiveness, the edges will be understood as conforming generally to the shape of the struts used to define the different vertices of the triangles.

The triangular shapes defined by the plurality of struts in the illustrative embodiment of the cage as seen in <FIG> are only one example of the triangular shapes that may be used in connection with filter bag assemblies and air filter systems as described herein. In general, however, one or more embodiments of the filter bag assemblies described herein may be described as having a bottom surface <NUM> of filter media having a width measured between the bottom edges of the side surfaces <NUM> (as defined by the bottom struts <NUM> and <NUM>) that is less than a height of either of the side surfaces <NUM> as measured between their top edges and bottom edges (where the top edges are defined by the top strut <NUM> and the bottom edges are defined by the bottom struts <NUM> and <NUM>). In one or more embodiments, the width of the bottom surface <NUM> may be <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, <NUM>% or less, or <NUM>% or less of the height of either side surface <NUM> of the pair of side surfaces. At a lower end, the width of the bottom surface may be <NUM>% or more, <NUM>% or more, <NUM>% or more, <NUM>% or more, <NUM>% or more, <NUM>% or more, <NUM>% or more of the height of either side surface of the pair of side surfaces. The width and height as discussed herein are measured transverse to the cage axis <NUM>, i.e., as seen in, e.g., <FIG>.

Other features depicted in the cross-sectional views of <FIG> include filter guide <NUM> which, in the depicted illustrative embodiment, extends from the tubesheet <NUM> to the access panel <NUM> of the dirty air chamber <NUM>. In the depicted illustrative embodiment, the filter guide <NUM> defines a guide axis <NUM> passing through the tubesheet <NUM> and the access panel <NUM>. The depicted guide axis <NUM> is aligned with the cage axis <NUM> and, although, the two axes <NUM> and <NUM> may be parallel with each other, a perfectly parallel arrangement is not required.

Filter guide <NUM> includes an entry end <NUM> at which the guide aperture <NUM> on the flange assembly <NUM> can be threaded, guided, or otherwise directed onto the filter guide <NUM> so that the flange assembly <NUM> can be supported on the filter guide <NUM>. In one or more embodiments, the entry end <NUM> of the filter guide <NUM> may be located closer to the access panel <NUM> of the air filter system than the tubesheet <NUM> against which the flange assembly <NUM> is forced as described herein.

Although the filter guide <NUM> extends from the tube sheet <NUM> to the access panel <NUM> in some of the depicted illustrative embodiments described herein, in one or more alternative embodiments, the filter guide <NUM> may only extend partially across the dirty air chamber such that, e.g., the filter guide <NUM> may terminate at a location short of the access panel <NUM> or even short of the tube sheet <NUM>. In one alternative embodiment, for example, the filter guide <NUM> may extend from the tubesheet <NUM> towards the access panel <NUM> but terminate short of the access panel <NUM>.

The filter guide <NUM> is located within a guide aperture <NUM> formed in the flange assembly <NUM>. The combination of the filter guide <NUM> and the guide aperture <NUM> formed in the flange assembly <NUM> provides support to the flange assembly <NUM> during insertion and removal of a filter bag assembly from the dirty air chamber <NUM> of the air filter system <NUM>. In particular, it may be preferred that the filter guide <NUM> and guide aperture <NUM> allow for translational or sliding movement of the flange assembly <NUM> through an access port in the access panel <NUM> to the tubesheet <NUM>. Although the depicted filter guide <NUM> and guide aperture <NUM> in the flange assembly <NUM> have similar shapes, any suitable combination of shapes for both the filter guide and the guide aperture may be used.

Some alternative embodiments of filter guides and guide apertures are depicted in <FIG>. In <FIG>, the filter guide <NUM>' has a T-shaped profile and the guide aperture <NUM>' in flange assembly <NUM>' has a complementary shape configured to accept the filter guide <NUM>'. In <FIG>, the filter guide <NUM>" has an inverted T-shaped profile and the guide aperture <NUM>" in flange assembly <NUM>" has a complementary shape configured to accept the filter guide <NUM>". In <FIG>, the filter guide <NUM>‴ has a round profile and the guide aperture <NUM>‴ in flange assembly <NUM>‴ has a complementary shape configured to accept the filter guide <NUM>"'. Many other alternative shapes for filter guides and guide apertures could also be provided.

In addition to providing support to the flange assembly <NUM> in a vertical direction, the combination of filter guide <NUM> and guide aperture <NUM> may, in one or more embodiments, also serve to limit or prevent rotation of the flange assembly around the guide axis <NUM> so that proper alignment of the flange assembly <NUM> on the tubesheet <NUM> may be achieved. To limit or prevent such rotation, the filter guide <NUM> and guide aperture <NUM> on the flange assembly <NUM> may have a noncircular shapes, with the tri-lobed and T-shaped examples of the depicted illustrative embodiments providing examples of only some noncircular shapes that may limit or prevent rotation of the flange assembly <NUM> relative to the guide axis <NUM>.

In one or more embodiments, the filter guide <NUM> may include a dust cover to prevent accumulation of particulate matter on the filter guide <NUM> that could be dislodged during removal of the filter bag assembly (e.g., as the flange assembly <NUM> moves from the tubesheet <NUM> towards the access panel <NUM>).

Other features depicted in the cross-sectional views of <FIG> include the clean air outlet <NUM> provided in the flange assembly <NUM> which allows both clean air to exit the interior volume of the filter bags <NUM> and also allows for pulses of air or other gases to enter the interior volume during a pulse cleaning process. In one or more embodiments, the clean air outlet may be described as having an elongated shape that extends from a top end (closest to the top strut <NUM>) and a bottom end (closest to the bottom struts <NUM> and <NUM>). The top end and the bottom end of the clean air outlet <NUM> may further be described as defining an outlet axis <NUM> that extends between the top and bottom ends of the clean air outlet <NUM>. In one or more embodiments, a projection of the outlet axis <NUM> along the cage axis <NUM> passes between the pair of bottom vertices of the triangles defined by the plurality of struts (where those bottom vertices are defined by the bottom struts <NUM> and <NUM>). Further, the projection of the outlet axis <NUM> passes through the top vertex (as defined by the top strut <NUM>) of the triangles defined by the plurality of struts.

Although not depicted in <FIG>, will be understood that tubesheet <NUM> includes a tubesheet aperture formed therethrough that is at least as large as the clean air outlet <NUM> provided in the flange assembly <NUM> such that the tubesheet aperture does not restrict airflow through the clean air outlet <NUM> into or out of the interior volume of the filter bag <NUM>. Furthermore, the tubesheet aperture may also be described as having a size that is smaller than the flange assembly <NUM> such that the flange assembly <NUM> can close or seal the tubesheet aperture such that air passing between the clean air chamber <NUM> and dirty air chamber <NUM> must pass through a clean air outlet <NUM> when the air filter system <NUM> is operational.

The cross-sectional views of <FIG> also depicts the alignment between pulse generators <NUM> and the clean air outlet <NUM> of the flange assemblies <NUM> in the depicted illustrative embodiment of air filter system <NUM>. In particular, the pulse generators <NUM> may be aligned with the clean air outlet <NUM>. Even more particularly, the pulse generator axis <NUM> may be aligned with the outlet axis <NUM> when viewed along the cage axis <NUM> as seen in <FIG>.

The views of <FIG> further depict the ports <NUM> of pulse generator <NUM>. In particular, the ports <NUM> to face the clean air outlet <NUM> and the aperture in the tubesheet <NUM>. Air delivered through the ports <NUM> of the pulse generator <NUM> passes through those ports and into the clean air outlet <NUM> formed in flange assembly <NUM>.

Because the filter bags used in air filter systems as described herein have generally triangular shapes, various features may be incorporated into the ports <NUM> of the pulse generators <NUM> facilitate the pulse cleaning process. For example, in one or more embodiments, the ports <NUM> closer to the bottom end of the clean air outlet <NUM> (i.e., closer to the bottom <NUM> of the filter bag <NUM>) may be larger in size than ports <NUM> located closer to the top end of the clean air outlet <NUM> (i.e., closer to the top edges of the sides <NUM> of the filter bag <NUM>). Alternatively, or in addition, the spacing between ports <NUM> may vary along the pulse generator axis <NUM>. For example, the spacing between the ports <NUM> located closer to the bottom end of the clean air outlet <NUM> may be smaller than the spacing between the ports <NUM> located closer to the top end of the clean air outlet <NUM>. Such variations in size and/or spacing of the ports <NUM> may facilitate the pulse cleaning process by providing more air and or higher pressures within the filter bag <NUM> proximate the bottom surface <NUM>.

A comparison of <FIG> illustrates the beneficial effects of the triangular-shaped filter bags described herein with respect to particular loading and pulse cleaning. In particular, as seen in <FIG> the triangular shaped filter bag <NUM> includes a bottom surface <NUM> that faces downwardly away from the dirty air inlet <NUM> into dirty air chamber <NUM> (see, e.g., <FIG>). Particulate matter introduced into the dirty air chamber <NUM> above the triangular filter bag <NUM> does not, therefore, impinge directly on or, under the force of gravity alone, collect on the bottom surface <NUM> of the filter bag <NUM>. This improves particulate loading performance of the filter bag <NUM>.

Improvements in pulse cleaning performance are also provided by the triangular-shaped filter bag <NUM> because particulate matter that does collect on the bottom surface <NUM> of the filter bag <NUM> is directed downwardly away from the bottom surface <NUM> during pulse cleaning. With reference to <FIG>, the bottom surface <NUM> of the filter bag <NUM> is forced outwardly/downwardly during pulse cleaning. By virtue of the nature of pulse cleaning, that outward/downward movement of the bottom surface <NUM> is a result of rapid acceleration which imparts a force to any dislodged particulate matter released from the bottom surface <NUM>, with the vector of that pulse cleaning force being generally aligned with the force of gravity to enhance movement of any dislodged particulate matter into a collection area such as, e.g., hopper <NUM> of air filter system <NUM>.

In addition to the beneficial effects of the bottom surface <NUM> of the triangular-shaped filter bags <NUM> of air filter systems as described herein, the side surfaces <NUM> of the filter bags <NUM> are also rapidly accelerated outward during pulse cleaning as seen in the changed positions of the sides <NUM> of filter bag <NUM> between <FIG>. As discussed herein, such movement of the sides <NUM> of the triangular-shaped filter bags <NUM> provides many of the same advantages in pulse cleaning performance associated with conventional envelope-shaped filter bags having vertical sides.

<FIG> is a simplified schematic diagram of components of the illustrative embodiment of air filter system <NUM> depicting one illustrative embodiment of a seal formed using a filter bag assembly in an air filter as described herein. In the depicted illustrative embodiment, the filter bag assembly includes a flange assembly <NUM>' and a cage <NUM>' attached to the flange assembly <NUM>'.

A filter bag <NUM>' is attached to the filter bag assembly, with bag opening <NUM>' being sealed against flange assembly <NUM>' and the cage <NUM>' located within the interior volume defined by the filter bag <NUM>'. For reference, clean air outlet <NUM>' extends along an outlet axis <NUM>' in a manner similar to the outlet axis <NUM> depicted in, e.g., <FIG>.

Cage <NUM>' defines a cage axis <NUM>' that extends through clean air outlet <NUM>' defined in flange assembly <NUM>'. Cage <NUM>' may also be described as including a first cage and attached to the flange assembly <NUM>' and a second cage end distal from the flange assembly <NUM>' along the cage axis <NUM>'. The second cage and of the cage <NUM>' may also be described as being proximate the second end <NUM>' of the filter bag <NUM>'.

Tubesheet <NUM>' includes aperture <NUM>' formed through the tubesheet <NUM>'. Clean air chamber <NUM>' and dirty air chamber <NUM>' are also indicated in <FIG>, with the two chambers being separated by the tubesheet <NUM>'. Flange assembly <NUM>' is positioned over the aperture <NUM>' in tubesheet <NUM>' such that air passing into and out of the interior volume of the filter bag <NUM>' from the clean air chamber <NUM>' passes through the aperture <NUM> ' and the clean air outlet <NUM>' in the flange assembly <NUM>'.

<FIG> also depicts the access panel <NUM>' located opposite tubesheet <NUM>' across the dirty air chamber <NUM>'. Access port <NUM>' is provided in access panel <NUM>' to allow for removal and replacement of the filter bag assembly (including flange assembly <NUM>', filter bag <NUM>', and cage <NUM>' attached to flange assembly <NUM>' and located within the interior volume of the filter bag <NUM>'). Access port <NUM>' is closed by cover <NUM>' to seal the dirty air chamber <NUM>' during operation of the air filter system.

Also depicted in <FIG> is a seal <NUM>' located between a tubesheet face of the flange assembly <NUM>' and the tubesheet <NUM>'. Seal <NUM>' is located around aperture <NUM>' in tubesheet <NUM>' as well as being located around clean air outlet <NUM>' in flange assembly <NUM>'. Seal <NUM>' ensures that air passing into the interior volume of the filter bag <NUM>' must pass either through the filter media forming filter bag <NUM>' (during, e.g., filtering) or the clean air outlet <NUM>' and aperture <NUM>' in tubesheet <NUM>. In other words, the seal <NUM>'between flange assembly <NUM>' and tubesheet <NUM>' prevents air (and preferably any particulate matter) from passing between the tubesheet face of the flange assembly <NUM>' and the tubesheet <NUM>' during operation of an air filter system as described herein.

In one or more embodiments, seal <NUM>' may be formed by compression between the flange assembly <NUM>' and the tubesheet <NUM>'. In one or more embodiments, a seal actuator may be provided to apply a seal force on the cage <NUM>' of the filter bag assembly. In such embodiments, the seal force is preferably directed along the cage axis <NUM> towards the tubesheet <NUM>'. In one or more embodiments, the seal force may be described as being directed through the second end <NUM>' of the filter bag <NUM>' and further being transferred to the seal <NUM>' through the filter bag <NUM>', cage <NUM>', and flange assembly <NUM>'. In particular, the cover <NUM>', which functions as the seal actuator in the depicted illustrative embodiment, acts on the second end <NUM>' of the filter bag <NUM>' which, in turn, acts on the second cage end of the cage <NUM>', with the cage <NUM>' transferring that force to the flange assembly <NUM>' by virtue of its attachment to the flange assembly <NUM>'.

Seal <NUM>' may be constructed of any suitable material and/or structures. Although many seals may be formed by compression of one or more resilient and/or elastomeric materials (in, e.g., O-rings, gaskets, etc.), other seal constructions may also be used to form the required seal between the flange assembly and the tubesheet in air filter systems as described herein when the flange assembly is subjected to a compression force (e.g., knife edge seals, radial seals, axial seals, etc.).

<FIG> is a perspective view of a portion of the tubesheet <NUM>, with the illustrative embodiment of a filter bag assembly including a filter bag <NUM> supported on the illustrative embodiment of filter guide <NUM>. As discussed herein, the filter bag assembly, including flange assembly <NUM> and filter bag <NUM> are supported on the filter guide <NUM>, with the flange assembly <NUM> forming a seal with the tubesheet <NUM>.

In one or more embodiments of the filter bags and air filter systems described herein, a bag support may be provided proximate the second end of the filter bag, i.e., the end of the filter bag distal from the flange assembly, with the bag support configured to prevent or limit sagging of the filter bag assembly at the second end of the filter bag due to, e.g., the weight of the cage located in the filter bag. In one or more embodiments of the filter bags, filter bag assemblies, and/or air filter systems described herein, the bag support may be provided on filter bag itself, as a part of the air filter system, and/or include components provided as a part of the filter bag and as a part of the air filter system.

The filter bag assembly depicted in <FIG> includes one illustrative embodiment of a bag support in the form of a bag support connector <NUM> attached to the filter bag <NUM> proximate the second end <NUM> of the filter bag <NUM> and a chamber connector <NUM> that is positioned in the dirty air chamber proximate the access panel <NUM> of the housing. In the depicted embodiment the chamber connector <NUM> is located on the filter guide <NUM> although such positioning is not required. The bag support connector <NUM> and the chamber connector <NUM> are configured to interlock with each other to support the second end of the filter bag <NUM> in the dirty air chamber (with the first end of the filter bag <NUM> being supported by the flange assembly <NUM> in cooperation with the filter guide <NUM> as described herein).

In the embodiment of a bag support as depicted in <FIG>, the bag support connector <NUM> is in the form of a loop while the chamber connector <NUM> is in the form of a hook, with the loop <NUM> connecting to the hook <NUM> to support the second end <NUM> of the filter bag <NUM>. Many variations are, of course possible. For example, the bag support connector <NUM> on the filter bag <NUM> may be in the form of a hook while the chamber connector <NUM> is in the form of a loop or aperture configured to receive the hook.

<FIG> depicts one alternative embodiment of a bag support that may be used to prevent or limit sagging of a filter bag assembly at the second end of the filter bag. In the depicted embodiment, the bag support includes the chamber connector <NUM> on filter guide <NUM> similar to that depicted in <FIG> which, in the depicted embodiment, is attached to access panel <NUM>" (with cover <NUM>" closing the access opening in the access panel <NUM>" as described herein). The embodiment of a bag support depicted in <FIG> includes a sling <NUM>" that may, for example wrap around the bag <NUM>", with the sling <NUM>" forming a loop that is configured to connect to the hook <NUM> on filter guide <NUM>. In one or more embodiments, the sling <NUM>" may be attached to the filter bag <NUM>" using one or more of, e.g., sewing, adhesives, etc. such that the sling <NUM>" is replaced with the filter bag <NUM>". Alternatively, the sling <NUM>" may be separate, e.g., unattached, to the filter bag <NUM>" such that the sling <NUM>" can be re-used with two or more different filter bags <NUM>".

<FIG> depicts yet another alternative embodiment of a bag support that may be used to prevent or limit sagging of a filter bag assembly at the second end of a filter bag. In the depicted embodiment, the bag support <NUM>"' is in the form of a surface provided proximate the bottom of the filter bag <NUM>"'. The bag support <NUM>"' may be attached to the access panel <NUM>‴ and may be accessed through the opening in the access panel <NUM>‴ that is closed by cover <NUM>"'. In one or more embodiments, the bag support <NUM>"' may be moved downward (away from the bag axis <NUM>) to assist with replacement of the filter bag <NUM>"'. Movement of the bag support <NUM>"' may include one or both of translational and rotational movement of the bag support <NUM>"'.

<FIG> is a perspective view of one illustrative embodiment of a portion of a access panel <NUM> including one illustrative embodiment of a cover <NUM> used to close a filter access port <NUM> formed in the access panel <NUM> through which filter bag assemblies including filter bags <NUM> can be removed from and inserted into the dirty air chamber <NUM> of the air filter system <NUM>. The illustrative embodiment of cover <NUM> includes a latch <NUM> and catch <NUM> to secure the cover <NUM> in a closed position (see the covers <NUM> to the right of the open cover <NUM>). The covers <NUM> may be connected to the access panel <NUM> for rotation about a hinge axis <NUM> such that the covers <NUM> can be moved from a closed position to an open position in which filter bag assemblies can be inserted into or removed from the dirty air chamber through access port <NUM>.

Rotation of the cover <NUM> about hinge axis <NUM> moves the cover <NUM> to its closed position in which cover <NUM> covers filter access port <NUM>. When in the closed position, the cover <NUM> may, in addition to closing filter access port <NUM>, function as a seal actuator such that the cover <NUM> also acts on the second ends <NUM> of the filter bags <NUM> to force an attached flange assembly against a tubesheet to form a seal as described herein. The forces provided by the cover <NUM> acting as a seal actuator when closed may be described as acting along the cage axes <NUM>.

<FIG> is a perspective view of the access panel <NUM> of <FIG> including an alternative illustrative embodiment of a cover <NUM>' used to close a filter access port <NUM> formed in the access panel <NUM> through which filter bag assemblies including filter bags <NUM> can be removed from and inserted into the dirty air chamber of the air filter system including access panel <NUM>. This illustrative embodiment of cover <NUM>' also includes a latch <NUM> and catch <NUM> to secure the cover <NUM>' in a closed position (see the cover <NUM>' to the right of the open cover <NUM>'). The covers <NUM>' may also be connected to the access panel <NUM> for rotation about a hinge axis <NUM> such that the covers <NUM>' can be moved from a closed position to an open position in which filter bag assemblies can be inserted into or removed from the dirty air chamber through access port <NUM>.

Rotation of the covers <NUM>' about hinge axis <NUM> moves the covers <NUM>' to their closed positions in which covers <NUM>' close filter access port <NUM>. When in the closed position, the covers <NUM>' may, in addition to closing filter access port <NUM>, function as seal actuators such that the covers <NUM>' also act on the second ends <NUM> of the filter bags <NUM> to force an attached flange assembly against a tubesheet to form a seal as described herein. The forces provided by the covers <NUM>' acting as seal actuators when closed may be described as acting along the cage axes <NUM>.

An additional feature depicted in covers <NUM>' are the embossments <NUM> provided in cover <NUM>'. The embossments <NUM> may, in one or more embodiments, have shapes that are complementary to the shape of the ends <NUM> of the filter bags <NUM>. Such embossments may provide advantages such as, for example, additional stability to the filter bag assemblies proximate the access panel <NUM>, more uniform force distribution over the second ends <NUM> of the filter bags <NUM> and, therefore, over the cages located within the filter bags <NUM> in filter bag assemblies as described herein, verification of proper installation of the filter bag assemblies (such that, for example, the bottom surfaces of triangular filter bags are properly oriented in a dirty air chamber), etc. In embodiments that include such embossments, a bag support configured to support the second end of the filter bag (as discussed above in connection with, e.g., <FIG>) may be helpful in ensuring that the second ends <NUM> of the filter bags <NUM> are properly positioned as the covers <NUM> ' are closed.

<FIG> is an exploded diagram of the filter bag assembly of <FIG> depicting the filter bag <NUM> removed from the cage <NUM> and, in addition, the clamp <NUM> of flange assembly <NUM> being removed from the base <NUM>. As discussed in connection with other embodiments of filter bags described herein, filter bag <NUM> includes an opening <NUM> at its first end and a bag support connector <NUM> proximate the second end of the filter bag <NUM>.

<FIG> also depicts the cage <NUM> including a top strut <NUM> and pair of bottom struts <NUM> and <NUM>, all of which are, in the depicted embodiment, aligned with the cage axis <NUM>. Cage <NUM> also includes braces <NUM> extending between the top strut <NUM> and the bottom struts <NUM> and <NUM>. At the location of each of the side braces <NUM>, bottom braces <NUM> may also be provided between the bottom struts <NUM> and <NUM> to maintain the triangular shape of the cage <NUM> by properly positioning the bottom struts <NUM> and <NUM>.

Another feature depicted in connection with <FIG> is that a pulse collector <NUM> may be attached to the flange assembly <NUM>, in particular, to the base <NUM> of the depicted flange assembly <NUM>. As a result, removal of the filter bag assembly would include removal of the pulse collector <NUM> along with the flange assembly <NUM>, cage <NUM> and filter bag <NUM>. In such a system, the tubesheet aperture <NUM> in tubesheet <NUM> is preferably sized to accommodate the pulse collector <NUM>. Furthermore, a seal may preferably be provided on the tubesheet face of the flange assembly to seal the junction between the flange assembly <NUM> and the tubesheet <NUM> as described herein.

<FIG> depict another illustrative embodiment of components of a filter bag assembly as described herein including a flange assembly <NUM> and cage <NUM> attached to the flange assembly <NUM>. The filter bag that would be provided over the cage <NUM> with an opening attached to the flange assembly <NUM> is not depicted in <FIG> and <FIG> for clarity.

The flange assembly <NUM> depicted in <FIG> includes a clamp <NUM> and base <NUM>, with the clamp <NUM> and base <NUM> shown as separated from each other along the cage axis <NUM> in <FIG>. The depicted flange assembly <NUM> also includes a clean air outlet <NUM> that is elongated along an outlet axis <NUM>. A guide aperture <NUM> is provided at the top of the flange assembly <NUM> for use with a filter guide as described in connection with other illustrative embodiments presented herein. A portion of seal <NUM> which is located on the tubesheet face of the flange assembly <NUM> and which extends around the clean air outlet <NUM> is also depicted in <FIG>.

The cage <NUM> depicted in <FIG> includes a top strut <NUM> and a pair of bottom struts <NUM> and <NUM>, all of which are, in the depicted embodiment, aligned with the cage axis <NUM>. Cage <NUM> also includes braces <NUM> extending between the top strut <NUM> and the bottom struts <NUM> and <NUM>. The depicted cage <NUM> also includes an intermediate strut <NUM> aligned with the cage axis <NUM>. The additional intermediate strut <NUM> may provide further structural integrity to the cage <NUM> and may, in one or more embodiments, enhance the uniformity of any seal force transferred through the cage <NUM> the flange assembly <NUM> form a seal as described herein.

Another feature depicted in <FIG> is a pulse collector <NUM> attached to the flange assembly <NUM>. In one or more embodiments, removal of a filter bag assembly including flange assembly <NUM> and cage <NUM> would also remove the pulse collector <NUM>.

An enlarged cross-sectional view of a portion of the components depicted in <FIG> is provided in <FIG>, with the tubesheet <NUM> and tubesheet aperture <NUM> also being depicted in <FIG>. It should be understood that only those components actually visible in the plane of the cross-sectional view are depicted in <FIG>. Both the outlet axis <NUM> and the cage axis <NUM> are depicted in <FIG> for reference.

With reference to <FIG>, the base <NUM> and clamp <NUM> of the flange assembly <NUM> are seen in <FIG> along with the bag opening <NUM> of filter bag <NUM> being clamped between the base <NUM> and clamp <NUM>. Clean air outlet <NUM> formed in the base <NUM> of the flange assembly provides for passage of air into or out of the interior volume defined by the filter bag <NUM> as described herein.

In one or more embodiments, the filter media forming the filter bag opening <NUM> may, itself, provide for seal between the flange assembly and the filter bag opening <NUM> that is sufficient to prevent leakage such that air entering or leaving the interior volume of the filter bag <NUM> must pass through the filter media of the bag or the clean air outlet <NUM>. Alternatively, additional seals and/or sealing material may be provided to prevent unwanted passage of air between the flange assembly and the filter bag opening <NUM>. For example, the bag opening <NUM> may include a compressible seal/cuff (similar to that found in, e.g., cuff <NUM> of filter bag <NUM> depicted in <FIG>) that may enhance sealing of the bag opening <NUM> between the base <NUM> and the clamp <NUM> to prevent the passage of air and/or particulate matter through the interface between the base <NUM>, the clamp <NUM>, and filter bag opening <NUM>.

The tubesheet face of the clamp assembly (i.e., the face of base <NUM> facing tubesheet <NUM>) acts on seal <NUM> which is located between base <NUM> and tubesheet <NUM> prevent the passage of air and/or particulate matter between the flange assembly base <NUM> and the tubesheet <NUM> during operation of an air filter system. Pulse collector <NUM> is depicted as being attached to the base <NUM> of the flange assembly in this illustrative embodiment.

As discussed herein, the filter bags used in the filter bag assemblies of air filter systems described herein are made of generally flexible filter media, the filter bags may not form particularly distinct triangles when viewed in cross-section. In general, however, the triangular-shaped filter bags and their associated cages can be described using the geometry of triangles with an understanding that the edges, sides, and vertices of such triangles will be generally approximated by the triangular cages and filter bags fitted thereon.

With that understanding, reference is made to <FIG> in which various triangular-shaped bag constructions that may be used in one or more embodiments of filter bag assemblies and air filter systems using the filter bag assemblies as described herein.

The idealized triangular-shaped bag <NUM> depicted in <FIG> is, in many respects, similar to the triangular-shaped bag <NUM> discussed herein with respect to various embodiments of the filter bag assemblies and air filter systems described above. The triangular-shaped bag <NUM> includes a top vertex <NUM> and a pair of bottom vertices <NUM> and <NUM>. A pair of side surfaces <NUM> extend between the top vertex <NUM> and each of the bottom vertices <NUM> and <NUM>. A bottom surface <NUM> extends between the bottom vertices <NUM> and <NUM>.

To further illustrate the difference between an idealized triangular-shaped defined by one or more embodiments of filter bags as described herein and the actual shapes taken by filter bags located on cages that provide the triangular shapes, the struts of cage <NUM> as seen in <FIG> are included in <FIG> along with cage axis <NUM> (which extends perpendicularly out of the paper on which <FIG> is located). In particular, top strut <NUM>, bottom struts <NUM> and <NUM>, and intermediate struts <NUM> are depicted inside filter bag <NUM> in <FIG>. It should be noted that top strut <NUM> may, as depicted in this illustrative embodiment be formed as a composite of two members. Such a construction may provide filter bag <NUM> with a small flat surface along its top edge. Reference can be had to, e.g., <FIG> and <FIG> where filter bag <NUM> has a relatively small flat top edge as a result of a somewhat widened top strut. Regardless of the slight deviations from a perfect triangle, it can be seen that the side surfaces <NUM> and bottom surface <NUM> of the filter bag <NUM> take on a generally triangular shape as described herein.

The bottom surface <NUM> may be described as having a width wb extending between the bottom vertices <NUM> and <NUM>. The left side surface <NUM> may be described as having a height s1 measured between the top vertex <NUM> and bottom vertex <NUM>. The right side surface <NUM> may be described as having a height s2 measured between the top vertex <NUM> and bottom vertex <NUM>. As discussed herein the width of the bottom surface (wb) is preferably less than the height of either of the side surfaces (s1 or s2).

Although not required, the depicted triangular-shaped bag <NUM> forms a triangle that may be described as being an acute triangle and, optionally, an isosceles triangle (in which s1 = s2). In the case of an isosceles triangle, the axis <NUM> depicted in <FIG> may be described as being an altitude of the triangle formed by the filter bag <NUM>.

The triangular-shaped bag <NUM> may further be described with respect to the angle formed by the side surfaces <NUM>. In particular, the angle α (alpha) formed by side surfaces <NUM> at vertex <NUM> may be selected such that the width (wb) of the bottom surface <NUM> has a selected relationship with the heights of the side surfaces <NUM>. In one or more embodiments, the angle α (alpha) may be <NUM>° or less, <NUM>° or less, <NUM>° or less, <NUM>° or less, <NUM>° or less, <NUM>° or less, or <NUM>° or less. At a lower end, the angle α (alpha) may be, in one or more embodiments, <NUM>° or more, <NUM>° or more, <NUM>° or more, or <NUM>° or more.

<FIG> depicts one alternative triangular-shaped filter bag that may be used in one or more embodiments of a filter bag assembly and/or air filter system as described herein. The triangular-shaped bag <NUM> includes a top vertex <NUM> and a pair of bottom vertices <NUM> and <NUM>. A pair of side surfaces <NUM> extend between the top vertex <NUM> and each of the bottom vertices <NUM> and <NUM>. A bottom surface <NUM> extends between the bottom vertices <NUM> and <NUM>. When mounted on a cage in a filter bag assembly as described herein, the cage axis would extend perpendicularly out of the paper on which <FIG> is located.

The triangular-shaped bag <NUM> may optionally be described with respect to the angle formed between the side surfaces <NUM> at vertex <NUM>. In particular, the angle α (alpha) formed by side surfaces <NUM> at vertex <NUM> may be selected such that the width (wb) of the bottom surface <NUM> has a selected relationship with the heights of the side surfaces <NUM>. In one or more embodiments, the angle α (alpha) may be <NUM>° or less, <NUM>° or less, <NUM>° or less, <NUM>° or less, <NUM>° or less, <NUM>° or less, or <NUM>° or less. At a lower end, the angle α (alpha) may be, in one or more embodiments, <NUM>° or more, <NUM>° or more, <NUM>° or more, or <NUM>° or more.

The depicted triangular-shaped bag <NUM> forms a triangle that may be described as being an obtuse triangle. The axis <NUM> depicted in <FIG> may be described as bisecting the angle α (alpha) and, as a result, the axis <NUM> also bisects the bottom surface <NUM>. In one or more embodiments of triangular-shaped filter bags as described herein, the axis passing through the top vertex and bisecting the angle formed at that vertex may preferably be oriented generally vertically within the dirty air chamber of an air filter system. With respect to the embodiment of triangular-shaped filter bag <NUM>, axis <NUM> may be oriented vertically or, alternatively, the axis <NUM> may canted or angled with respect to a vertical axis.

Although the bottom surface <NUM> of the triangular-shaped filter bag <NUM> may not be oriented transverse to the vertical axis, particulate matter dislodged from the bottom surface <NUM> during pulse cleaning would have a vertical force component that, when added to the force applied by gravity, would preferentially move the dislodged particulate matter downward as described in connection with other illustrative embodiments of filter bags described herein.

<FIG> depicts a pair of triangular-shaped filter bags <NUM>. The triangular -shaped filter bag <NUM> on the right side of <FIG> has essentially the same shape as the filter bag <NUM> depicted in <FIG>. The triangular-shaped filter bag <NUM> on the left side of <FIG> is a mirror image of the filter bag <NUM> on the right side of <FIG>. Both the left and right side triangular-shaped filter bags <NUM> include vertically oriented surfaces <NUM> facing each other and aligned with a vertical axis V, while the outer side surfaces <NUM> of the triangular-shaped filter bags <NUM> face away from each other. One potential advantage of such an arrangement is that the triangular-shaped filter bags <NUM> may be spaced closer together (in a direction transverse to the vertical axis), thus increasing the surface area of filter media available within a given dirty air chamber volume while retaining the particulate loading and pulse cleaning advantages that may be associated with triangular-shaped filter bags as described herein.

The depicted triangular-shaped bag <NUM> forms a triangle that may be described as being a right triangle. The axis <NUM> depicted in <FIG> may be described as bisecting the bottom surface <NUM>. In one or more embodiments of triangular-shaped filter bags as described herein, the axis passing through the top vertex and bisecting the bottom surface may be oriented generally vertically within the dirty air chamber of an air filter system. With respect to the embodiment of triangular-shaped filter bag <NUM>, axis <NUM> may be oriented vertically or, alternatively, the right side surface <NUM> (forming a right angle with the bottom surface <NUM>) may be oriented vertically such that the bottom surface <NUM> is oriented generally horizontally to a vertical axis. As used herein, the phrase "generally horizontal" (and variations thereof) means that the component or components (e.g., a filter bag and/or filter bag assembly with cage) is/are arranged such that the component or components form an angle of <NUM> degrees or less, <NUM> degrees or less, <NUM> degrees or less, or <NUM> degrees or less off of a horizontal line (where gravitational force vectors define the vertical axis). For example, the cage axis or filter bag axis may define such an angle with a horizontal line if the filter bag and/or cage is canted with respect to perfectly horizontal line.

Even if the bottom surface <NUM> of the triangular-shaped filter bag <NUM> is not oriented transverse to the vertical axis (where, for example, the axis <NUM> is oriented vertically), particulate matter dislodged from the bottom surface <NUM> during pulse cleaning would have a vertical force component that, when added to the force applied by gravity, would preferentially move the dislodged particulate matter downward as described in connection with other illustrative embodiments of filter bags described herein.

Another illustrative embodiment of a filter bag assembly supported on a filter guide attached to a tubesheet is depicted in a perspective view in <FIG>. The depicted filter bag assembly includes a flange assembly that, in the depicted embodiment, includes a base <NUM> and a clamp <NUM>, along with a filter bag <NUM> and a cage <NUM> attached to the base <NUM> of the flange assembly. A clean-air outlet <NUM> is formed in the base <NUM> of the flange assembly to allow for passage of air into or out of the interior volume of the filter bag <NUM>. The cage <NUM> extends away from the flange assembly along a cage axis <NUM> and is used to support filter bag <NUM> in a selected shape (e.g., triangular, as depicted).

The filter bag assembly of <FIG> also includes a pulse collector <NUM> attached to the base <NUM> of the flange assembly and configured to pass through the aperture <NUM> in tubesheet <NUM> when the filter bag assembly is properly positioned for use in a dirty air chamber.

The air filter system depicted in <FIG> also includes an alternative illustrative embodiment of a filter guide used to support the filter bag assembly (i.e., the flange assembly including base <NUM> and clamp <NUM>, filter bag <NUM>, and cage <NUM>). The depicted embodiment of a filter guide includes struts <NUM> that are attached to tubesheet <NUM> and extend away from tubesheet <NUM> along cage axis <NUM>. The struts <NUM> of this embodiment of a filter guide can be contrasted with the external filter guide <NUM> seen in, e.g., the illustrative embodiment depicted in <FIG> and <FIG>.

Another optional feature depicted in connection with the illustrative embodiment of a filter bag assembly and associated air filter system structure depicted in <FIG> is a cover <NUM> used to close an access port <NUM> in an access panel. The cover <NUM> includes embossments <NUM> that may, in one or more embodiments, be configured to have a shape that is complementary to the shape of the second end <NUM> of the filter bag <NUM>, as described herein, such embossments may provide advantages such as, for example, additional stability to the filter bag assemblies proximate the access panel, more uniform force distribution over the second end <NUM> of the filter bag <NUM> and, therefore, over the cage located within the filter bag <NUM>, verification of proper installation of the filter bag assemblies (such that, for example, the bottom surface of the triangular filter bag is properly oriented in the dirty air chamber), etc..

<FIG> is an enlarged partial cross-sectional view of the filter bag assembly of <FIG> depicting illustrative embodiments of the junctions between the flange assembly components, filter, and tubesheet. In particular, the view of <FIG> depicts filter bag <NUM> supported on filter cage <NUM>. Filter cage <NUM> is attached to the base <NUM> of the flange assembly with the bag opening <NUM> captured between the clamp <NUM> and base <NUM> of the flange assembly. The bag opening <NUM> may include a compressible seal/cuff (similar to that found in, e.g., cuff <NUM> of filter bag <NUM> depicted in <FIG>) that may enhance sealing of the bag opening <NUM> between the base <NUM> and the clamp <NUM> to prevent the passage of air and/or particulate matter through the interface between the base <NUM>, the clamp <NUM>, and filter bag opening <NUM>. Another optional component depicted in <FIG> is a clamp assembly <NUM> used to secure clamp <NUM> on base <NUM>, with opening <NUM> of filter bag <NUM> secured therebetween. Clamp <NUM> may take any of a suitable number of forms such as, e.g., a spring clamp assembly similar to those used in connection with, e.g., many other filter cartridges and elements.

<FIG> also depicts a seal <NUM> located on the base <NUM> of the flange assembly. The seal <NUM> faces the tubesheet <NUM> and, when the base <NUM> of the flange assembly is moved into contact with the tubesheet <NUM>, the seal <NUM> preferably forms a seal between the base <NUM> and the tubesheet <NUM> that prevents the passage of air and/or particulate matter through the interface between the flange assembly and the tubesheet <NUM> as described in connection with other illustrative embodiments herein.

<FIG> is a cross-sectional view of another illustrative embodiment of a filter bag assembly including an envelope-shaped filter bag <NUM> supported by a cage <NUM> on a flange assembly <NUM> as described herein. Although some illustrative embodiments of air filter systems and filter bag assemblies described herein may advantageously use filter bags and cages that result in triangularly shaped filter bags, many of the advantages and benefits associated with filter bag assemblies that are compressed within a dirty air chamber as described herein are also available in connection with filter bags on filter bag assemblies having any selected shape.

In particular, <FIG> depicts one embodiment of a more conventional envelope - shaped filter bag assembly in which the opposite major sides of the filter bag <NUM> are generally parallel to each other in use (e.g., have an angle α (alpha) that is essentially <NUM>° (with reference to <FIG>)). The filter bag <NUM> is mounted on a cage constructed of struts <NUM> that define the envelope shape of the filter bag <NUM> mounted thereon.

The struts <NUM> are attached to a flange assembly <NUM> that includes a clean air outlet <NUM> as described in connection with other embodiments of flange assemblies of filter bag assemblies as described herein. The clean air outlet <NUM> is, in the depicted illustrative embodiment elongated along an outlet axis <NUM> as described in connection with other illustrative embodiments herein.

The struts <NUM> of the cage attached to the flange assembly <NUM> also extend away from that flange assembly <NUM> along a cage axis <NUM> to a distal end where they support a second end of the filter bag <NUM> as described in connection with other illustrative embodiments herein. Also depicted in <FIG> are a portion of the tubesheet <NUM> against which flange assembly <NUM> is forced to provide a seal, along with an aperture <NUM> in the tubesheet <NUM> through which air passes into or out of the clean air chamber located on the opposite side of the tubesheet <NUM>.

<FIG> depict one illustrative embodiment of a triangular filter bag that may be used in one or more embodiments of filter bag assemblies and air filter systems as described herein. The triangular filter bag <NUM> includes an opening <NUM>, a closed end provided by a substantially triangular end cap <NUM>, and a body <NUM> extending from the opening <NUM> to the closed end along a bag axis <NUM> that extends between the opening <NUM> to the closed end of the filter bag <NUM>.

The body <NUM> of the triangular filter bag <NUM> is formed of filter media suitable for removing particulate matter from air in the application for which it is intended. In one or more embodiments, the body <NUM> may consist essentially of filter media with no other components provided. With reference to <FIG>, the body <NUM> may include seam edges <NUM> and <NUM> that are attached to each other to form a longitudinal seam <NUM>/<NUM> as seen in, e.g., <FIG>. When the seam edges <NUM>/<NUM> are attached to each other, the body may be described as taking a tubular shape that defines an interior volume between the opening <NUM> and the closed and defined by the triangular end cap <NUM>. In that tubular shape, the filter media of the body <NUM> also defines a closed end edge <NUM> located at the closed end of the filter bag <NUM> and an opening edge <NUM> located at the opening <NUM> of the filter bag <NUM>.

In one or more embodiments, the junction between the longitudinal seam <NUM>/<NUM> with the triangular end cap <NUM> may be located along one of the side edges <NUM> of the triangular end cap <NUM> between the bottom edge <NUM> and the apex <NUM> of the triangular end cap. In one or more alternative embodiments, a junction between a longitudinal seam and a triangular end cap of a filter bag as described herein may be located along the bottom edge <NUM> or the apex <NUM>. Further, although body <NUM> includes only one longitudinal seam <NUM>/<NUM>, one or more alternative embodiments of triangular filter bags as described herein may include two or more seams.

The triangular end cap of one or more embodiments of triangular filter bags as described herein may, with reference to the illustrative embodiment of triangular end cap <NUM>, include two side edges <NUM> that extend between a bottom edge <NUM> and an apex <NUM>. Described alternately, the side edges <NUM> of the triangular end cap <NUM> may be described as meeting at the apex <NUM> at a location distal from the bottom edge <NUM>.

To provide a filter bag capable of removing particulate matter from air, the filter media of the body <NUM> at the closed end edge <NUM> is sealed to the side edges <NUM>, bottom edge <NUM> and apex <NUM> of the triangular end cap <NUM> such that particulate matter is substantially prevented from passing through those junctions.

The triangular end cap <NUM> may, in one or more embodiments, define the generally triangular-shaped of the filter bag <NUM> along its length and will more definitely defined the triangular-shaped of the filter bag <NUM> proximate the triangular end cap <NUM>. With reference to <FIG>, the shape of the triangular end cap <NUM> can be described with reference to the included angle formed between the side edges <NUM> of the triangular end cap <NUM>. In particular, the bottom edge <NUM>, apex <NUM>, and side edges <NUM> of the triangular end cap <NUM> may, in one or more embodiments, be described as defining an included angle α (alpha) between the side edges <NUM> at the apex <NUM> of <NUM>° or less, <NUM>° or less, <NUM>° or less, <NUM>° or less, or <NUM>° or less. At a lower end, the angle α (alpha) may be, in one or more embodiments, <NUM>° or more, <NUM>° or more, <NUM>° or more, or <NUM>° or more.

The triangular end caps that may be used in one or more embodiments of triangular filter bags as described herein may alternatively be described with respect to the dimensions of the features of the triangular end cap. For example, the triangular end cap <NUM>, when projected onto a flat surface along the bag axis <NUM> may, in one or more embodiments, define a height (h) between the apex <NUM> and the bottom edge <NUM>. The projection of triangular end cap <NUM> may also define a width (w) across the bottom edge <NUM> between the side edges <NUM>. In one or more embodiments of triangular filter bags as described herein, the height (h) is greater than the width (w). More particularly, in one or more embodiments, the height (h) defined between the bottom edge and the apex of a triangular end cap may be <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, or <NUM> times or more the width (w) defined along the bottom edge between the sides of the triangular end. In one or more embodiments, the height (h) defined between the bottom edge and the apex of a triangular end cap may be, at an upper end, <NUM> or less, <NUM> or less, <NUM> or less, <NUM> or less, <NUM> or less, or <NUM> or less times the width (w) defined along the bottom edge between the sides of the triangular end. In one embodiment, the height (h) defined between the bottom edge and the apex of a triangular end cap may be <NUM> to <NUM> times the width (w) defined along the bottom edge between the sides of the triangular end. It should be noted that the height (h) is preferably measured along an end cap axis <NUM> that extends between the bottom edge <NUM> and the apex <NUM> and may, in one or more embodiments, be described as bisecting both the bottom edge <NUM> and the apex <NUM> and/or defining an axis of symmetry of the triangular end <NUM>. In one or more embodiments of filter bags including triangular end caps as described herein, the triangular end may be constructed of filter media, e.g., the same filter media used for the body <NUM> of the filter bag. In one or more alternative embodiments, the triangular end caps may be constructed of materials that are impermeable to air (unlike the filter media used for the body <NUM>). In one or more embodiments, the triangular end caps may be substantially rigid, self-supporting articles, while in other embodiments the triangle are end caps may be constructed of flexible materials that are not capable of self-support.

In one or more embodiments of filter bags including triangular end caps as described herein, the closed end edge <NUM> of the body <NUM> may be sealed to the side edges <NUM> of the triangular end cap <NUM> using any suitable technique or combination of techniques sufficient to provide structural integrity to that junction as well as limit/prevent passage of particulate matter through that junction. In one or more embodiments, the closed end edge may be sealed to the side edges using one or more of a sewn seam, a stitched seam, an adhesive seam, a chemically welded seam, and a thermally welded seam.

In one or more embodiments of filter bags including triangular end caps as described herein, the closed end edge <NUM> of the body <NUM> may be sealed to the bottom edge <NUM> of the triangular end cap <NUM> using any suitable technique or combination of techniques sufficient to provide structural integrity to that junction as well as limit/prevent passage of particulate matter through that junction. In one or more embodiments, the closed end edge may be sealed to the side edges using one or more of a sewn seam, a stitched seam, an adhesive seam, a chemically welded seam, and a thermally welded seam.

In one or more embodiments of filter bags including triangular end caps as described herein, the closed end edge <NUM> of the body <NUM> may be sealed to the apex <NUM> of the triangular end cap <NUM> using any suitable technique or combination of techniques sufficient to provide structural integrity to that junction as well as limit/prevent passage of particulate matter through that junction. In one or more embodiments, the closed end edge may be sealed to the side edges using one or more of a sewn seam, a stitched seam, an adhesive seam, a chemically welded seam, and a thermally welded seam.

With reference to <FIG>, filter bag <NUM> also includes an optional cuff <NUM> attached to the filter media of the body <NUM> along the opening edge <NUM> of the body <NUM>. The cuff <NUM> may, in one or more embodiments, be used to enhance sealing of the bag opening <NUM> to a flange assembly of a filter bag assembly as described herein. In one or more embodiments, the cuff <NUM> may be thicker than the filter media. In one or more embodiments, the cuff <NUM> may include one or more resilient, compressible materials or bodies (see, e.g., body <NUM> in <FIG>) suitable to enhance a seal formed between the bag opening <NUM> and a flange assembly of a filter bag assembly as described herein.

Claim 1:
An air filter system (<NUM>) comprising:
a tubesheet (<NUM>) separating a housing into a dirty air chamber (<NUM>) and a clean air chamber (<NUM>), wherein the tubesheet (<NUM>) comprises an aperture (<NUM>') placing the dirty air chamber (<NUM>) in fluid communication with the clean air chamber (<NUM>), and wherein the housing comprises an access panel (<NUM>) located across the dirty air chamber (<NUM>) from the tubesheet (<NUM>);
a filter bag assembly located in the dirty air chamber (<NUM>), the filter bag assembly comprising a flange assembly (<NUM>) covering the aperture in the tube sheet (<NUM>), a cage (<NUM>) comprising a first end attached to the flange assembly (<NUM>), the cage (<NUM>) extending away from the flange assembly (<NUM>) to a second end proximate the access panel (<NUM>), and a filter bag (<NUM>) comprising a bag opening (<NUM>) sealed within the flange assembly (<NUM>), wherein the cage (<NUM>) is located in an interior volume of the filter bag (<NUM>) with the second end of the cage (<NUM>) proximate a closed end of the filter bag (<NUM>);
an access port (<NUM>') in the access panel (<NUM>) proximate the second end of the cage (<NUM>), wherein the filter bag assembly passes through the access port (<NUM>') during placement in and removal from the dirty air chamber (<NUM>);
means for forcing the flange assembly (<NUM>) against the tubesheet (<NUM>) by applying a compression force on the second end of the cage (<NUM>), wherein the compression force acts on the second end of the cage (<NUM>) through the filter bag (<NUM>); and said air filter system being characterized in that it further comprises
a filter guide (<NUM>) in the dirty air chamber (<NUM>) and in that the flange assembly (<NUM>) is supported on the filter guide (<NUM>) when moving towards and away from the tubesheet (<NUM>).