Through-air apparatus to reduce infiltration of ambient air

A through-air apparatus for drying or bonding paper, tissue, or nonwoven webs is provided. The apparatus includes a web-carrying structure configured to move and a first component having at least one sealing element adjacent the web-carrying structure, where the sealing element is configured to reduce the infiltration of ambient air into the through-air apparatus. The apparatus also includes at least one channel configured to direct air to the sealing element to reduce the infiltration of ambient air into the through-air apparatus. A method of operating a through-air apparatus for drying or bonding paper, tissue, or nonwoven webs is also provided. The method includes directing air to a sealing element to reduce the infiltration of ambient air into the through-air apparatus.

FIELD OF THE INVENTION

The invention relates, in part, to a through-air apparatus for manufacturing web products, and methods of use, which reduce the infiltration of ambient air into the through-air apparatus.

BACKGROUND

“Through air technology” is a term used to describe systems and methods enabling the flow of air through a paper, tissue, or nonwoven web for the purpose of drying or bonding fibers or filaments. Examples include the drying of nonwoven products (e.g., tea bags and specialty papers); drying and curing of fiberglass mat, filter paper, and resin-treated nonwovens; thermobonding and drying of spunbond nonwovens; drying hydroentangled webs; thermobonding geotextiles with or without bicomponent fibers; drying and curing interlining grades; and thermobonding absorbent cores with fusible binder fibers. The drying of tissue paper is also another application of through air technology.

Systems and methods related to through-air drying are commonly referred to through the use of the “TAD” acronym. Systems and methods related to through-air bonding are commonly referred to through the use of the “TAB” acronym.

A through-air apparatus generally includes a rigid air-permeable web-carrying structure. A web is placed on the web-carrying structure, and as the web-carrying structure moves, a fan may blow air through the wall of the web-carrying structure to treat the web. The web-carrying structure typically has a plurality of openings to permit the air to pass through the structure.

SUMMARY OF THE INVENTION

In a first aspect, a through-air apparatus for drying or bonding paper, tissue, or nonwoven webs is provided. The apparatus includes a web-carrying structure configured to move, and a first component having at least one sealing element adjacent the web-carrying structure, where the at least one sealing element is configured to reduce the infiltration of ambient air into the through-air apparatus. The apparatus also includes at least one channel configured to direct air to the at least one sealing element to reduce the infiltration of ambient air into the through-air apparatus.

In another aspect, a method of operating a through-air apparatus for drying or bonding paper, tissue, or nonwoven webs is provided. The method includes placing a web on a portion of a web-carrying structure, and moving the web-carrying structure such that the web moves with the web-carrying structure. The method also includes providing a first component having at least one sealing element adjacent to the web-carrying structure, where the at least one sealing element on the first component is configured to reduce the infiltration of ambient air into the through-air apparatus. The method further includes directing air to the at least one sealing element to reduce the infiltration of ambient air into the through-air apparatus.

In yet another aspect, a through-air apparatus for drying or bonding paper, tissue, or nonwoven webs is provided. The apparatus includes a rotating web-carrying structure including a carrying surface having a plurality of openings to permit the passage of air, and a web wrap angle defining angular active and inactive zones of the web-carrying structure and creating active and inactive air flow zones of the through-air apparatus. The apparatus also includes a stationary structure which the rotating web-carrying structure rotates relative to, the stationary structure including one or more sealing elements configured to reduce in-leak of ambient air into the active zone of the through-air apparatus relative to an otherwise identical structure lacking the one or more sealing elements. The apparatus further includes one or more channels for the delivery of recirculated air, or other heated air stream, to one or more of the sealing elements thereby further reducing the in-leak of ambient air into the active zone of the through-air apparatus.

DETAILED DESCRIPTION

The present disclosure is directed to a through-air apparatus configured to manufacture various products, such as paper, tissue, and/or nonwoven webs. One of ordinary skill in the art would recognize that the through-air apparatus may be configured as a through-air dryer (TAD) and/or a through-air bonder (TAB), depending on the context in which the apparatus is used. One of ordinary skill in the art will also recognize that the through-air apparatus may be used to make various web products that are rolled in their finished end product form. It should also be recognized that the product may not be rolled and/or may be cut into a finished end product. Furthermore, one of ordinary skill in the art will also recognize that the through-air apparatus may be configured to make various products, including, but not limited to various films, fabric, or other web type material, and the apparatus may be used for various processes that may include mass transfer, heat transfer, material displacement, web handling, and quality monitoring, including, but not limited to drying, thermal bonding, sheet transfer, water extraction, web tensioning, and porosity measurement.

As set forth in more detail below, the through-air apparatus includes a rigid air-permeable web-carrying structure configured to move relative to another portion of the apparatus. A web is placed on the web-carrying structure, and as the web moves, a fan may blow air through the wall of the web-carrying structure to treat the web. The web-carrying structure typically has a plurality of openings to permit the air to pass through the structure. As discussed in more detail below and as shown inFIG.6-15, in certain embodiments, the web-carrying structure is a through-air roll configured for rotational movement about a first axis. As discussed below and as shown inFIG.16, in another embodiment, the web-carrying structure is a flatbed belt configured for translational movement along either a horizontal or inclined plane. It should be appreciated that the below described configurations may be incorporated into various types of through-air apparatus configurations that employ web-carrying structures that are configured for rotational and/or translational movement, as the disclosure is not limited in this respect.

In one particular embodiment, a web (i.e. product) is typically in a sheet-form and it is partially wrapped around a cylindrical shell (i.e. through-air roll) of the through-air apparatus. The web is wrapped about a portion of the roll ranging from, for example, 90° to 360°, and typically between 180°-300° around the roll. The cylindrical wall of the through-air roll typically has a plurality of openings configured for air to pass through. A fan/blower is used to circulate the air across the product, and the through-air roll is typically positioned within a hood to optimize the air flow characteristics. As the product travels with the rotating shell through the active zone of the apparatus, the fan/blower circulates air through the wall of the cylindrical shell to treat the product. A heater may be provided so that heated air circulates through the through-air roll.

A conventional through-air apparatus system diagram is illustrated inFIG.1. As shown, the through-air apparatus100includes a though-air roll120that is configured to rotate within a hood130. The system includes a main fan140that directs system air (also known as process air) through conduit170and into hood130and then draws the air into the through-air roll120. As shown, an air heater150may also be coupled to the conduit170to direct heated air into the through-air roll120. The system may also include an exhaust fan160to draw air out of the apparatus100through conduit170to vent to atmosphere. As shown inFIG.1, there is a closed loop of system air that flows from the main fan140through the conduit170, into the hood130, through the through-air roll120, out an exhaust duct and through conduit170.

A through-air apparatus100is typically a very large machine. For example, the through-air roll120may have a length between 1 foot-30 feet, and a diameter between 1 foot-22 feet. The cylindrical wall of the roll120may be formed of an open rigid structure to permit the flow of air therethrough. In one embodiment, the through-air roll120may be a HONEYCOMB ROLL® obtained from Valmet, Inc.

As mentioned above, the through-air apparatus100has an active air flow zone which is configured to receive the system air to treat the web. As shown inFIG.1, this active air flow zone is defined, in part, by the portion of the through-air roll120that is configured to receive the web product. As also shown inFIG.1, the through-air apparatus also has an inactive air flow zone which is defined, in part, by the portion of the through-air roll120that is not configured to receive the web product. As set forth in more detail below, these active and inactive zones may vary depending upon on how the web is wrapped around the through-air roll120.

The inventors recognized problems associated with the conventional through-air apparatus100shown inFIG.1. In particular, the inventors recognized that there was undesirable in-leak of ambient air into the through-air apparatus100. As set forth in more detail below, there is typically a space, or a gap between the web-carrying structure and adjacent components of the through-air apparatus100to enable movement of the web-carrying structure. This gap is generally between about 0.06 inches-0.375 inches. In this particular embodiment shown inFIG.1, the web-carrying structure is a rotating through-air roll120. One or more sealing elements (discussed below) may be provided on these adjacent components to reduce in-leak of ambient air. Nevertheless, infiltration of ambient air into the through-air apparatus still occurs in these locations. The inventors recognized that currently there is a limitation on how small the seal clearances can be set due to various factors, such as, the through-air roll size, width, operating vacuum, rotation speed, and loads. As set forth in more detail below, aspects of the present disclosure are directed to reducing and controlling this in-leak of ambient air into the through-air apparatus.

As set forth in more detail below, aspects of the present disclosure include directing air to at least one sealing element on one or more components of the through-air apparatus to reduce the infiltration of ambient air into the through-air apparatus. As discussed below, the air which is directed to the sealing element may be sourced from a variety of locations, including, but not limited to, recirculating the system air from another portion of the through-air apparatus system. In one embodiment, the air is sourced from the exhaust line of the through-air apparatus. Other air sources are also contemplated and are discussed below. For example, both heated and non-heated air sources not specifically within the through-air apparatus system may also be employed. As set forth below, at least one channel is provided in the through-air apparatus to direct this air to the sealing element.

The inventors contemplate that the present disclosure may have a variety of advantages. First, the concepts of the present disclosure may be employed to increase the energy efficiency of a through-air apparatus by recycling exhaust air, minimizing heat loss within, and/or reducing the infiltration of ambient air into the through-air apparatus. Second, the concepts discussed therein may be used to help regulate and/or control the system air humidity levels within the through-air apparatus. Third, the concepts of the present disclosure may enable larger gaps/spaces between the sealing elements and the web-carrying structure in comparison to a traditional through-air apparatus.

Details of various embodiments are described below, but first a high level overview of the various through-air apparatus schematic diagrams shown inFIGS.2-5contemplated by the inventors will be described.

The inventors developed novel through-air apparatus configurations that reduce the infiltration of ambient air into the through-air apparatus. As set forth in more detail below, the apparatus includes one or more channels for the delivery of air to one or more sealing elements.FIGS.2-5illustrate various schematic diagrams of through-air apparatus systems that illustrate the various sources of air contemplated by the present disclosure.FIGS.6-16(described below) illustrate various channel configurations within the through-air apparatus that direct the air to the sealing elements.

FIG.2illustrates a schematic diagram of one embodiment of a through-air apparatus system where heated air is delivered to at least one sealing element via a booster fan204. Similar toFIG.1, the through-air apparatus200includes a though-air roll120that is configured to rotate within a hood130. As shown, in one embodiment, the web-carrying structure is a through-air roll120. As set forth in more detail below and as shown inFIG.16, in another embodiment, non-rotating configurations are contemplated, and the web-carrying structure may include a flatbed belt configured for translational movement. As shown, a main fan140directs system air into the through-air apparatus200through conduit170and an air heater150may be employed to direct heated air into the through-air apparatus200. Furthermore, an exhaust fan160may be used to draw air out of the apparatus200.

Most notably, unlike the conventional apparatus shown inFIG.1, the through-air apparatus200shown inFIG.2further includes an additional conduit202that includes a booster fan204. As described in more detail below, the conduit202and booster fan204are configured to direct air to at least one sealing element in the through-air apparatus200. Details regarding how the air is directed to the sealing element is shown inFIGS.6-16and is described in more detail below. As shown, inFIG.2, the conduit202and booster fan204are used to specifically direct exhaust air from conduit170back into the at least one sealing element in the through-air apparatus200to reduce the infiltration of ambient air into the through air apparatus200.

FIG.3illustrates a schematic system diagram of another embodiment of a through-air apparatus300.FIG.3is identical toFIG.2, except that instead of the conduit202and booster fan204shown inFIG.2, the embodiment inFIG.3illustrates conduit302which is used to recirculate heated exhaust air to a sealing element in the through-air apparatus300. As mentioned above, details regarding how the air may be specifically directed to the sealing element is shown inFIGS.6-16and described in more detail below. In this embodiment, the conduit302is positioned downstream of the exhaust fan160, so that the exhaust fan160can be used to direct the air to a sealing element. Thus, in this particular embodiment, a separate booster fan204is not required.

The present disclosure also contemplates configurations where the air that is directed to the sealing element is not sourced specifically from the exhaust line. For example, as shown in the schematic system diagram shown inFIG.4, in one embodiment, the present disclosure contemplates a configuration where the air that is directed to the sealing element is delivered via the main fan140. As illustrated, a conduit402is provided which branches off from conventional conduit170between the main fan140and the air heater150. As set forth in more detail below, conduit402is configured to direct air to one or more sealing elements on the through air apparatus400. As also discussed in more detail below, the conduit402may include one or more flow control features, such as dampers404, to control the amount of air that flows to the sealing element, which may enable one to control/regulate humidity levels of the system air.

FIG.5illustrates a schematic diagram of another through-air apparatus system according to yet another embodiment. In this embodiment, air is delivered to the sealing element via a heated air source510, outside of the system air of the through-air apparatus system. Non-heated heat sources are also contemplated as the disclosure is not so limited. As shown, conduit502is configured to direct heated air from the heated air source510to the sealing element of the through-air apparatus500. For example, in one embodiment, the air source510may include pre-heated ambient air, turbine exhaust gas, Yankee hot air system exhaust air, vacuum pump exhaust air, other heated air streams in a paper machine or mill environment, or any other hot air source. Other embodiments may include non-heated air sources, as the present disclosure is not limited in this respect.

As shown inFIGS.2-5, the present disclosure contemplates various configurations where air is obtained from different sources (both within the through-air apparatus system and also from external sources outside of the system air of the through-air apparatus system), and the air is then directed into the through-air apparatus to at least one sealing element. Turning now toFIGS.6-16, details regarding how the air may be specifically directed to the one or more sealing elements on the through-air apparatus will now be described in more detail.

FIG.6illustrates a through-air apparatus600which includes a through-air roll610(i.e. rotating web-carrying structure) which is configured to rotate about a first axis602. As shown, a web620is wrapped around the roll610. The through-air roll610has a carrying surface612which has a plurality of openings to permit the passage of air. The apparatus600may also include rollers614which may assist in transfer of the web620onto and off of the roll610. A web wrap angle θ defines angular active and inactive zones of the web-carrying structure. As shown inFIG.6, the rollers614are positioned such that the inactive zone web wrap angle θ is about 110°, and thus, the active zone web angle is about 250°. One of ordinary skill in the art will recognize that these angles can vary as the present disclosure is not limited in this respect.

One of ordinary skill in the art will also recognize that these inactive and active zones of the web-carrying structure create corresponding active and inactive air flow zones of the through-air apparatus. As mentioned above, the active air flow zone of the through-air apparatus is the portion configured to receive the system air to treat the web. The active air flow zone of the through-air apparatus may be defined as an area which includes the web wrapped about the roll610and surrounding areas configured to receive system air through the conduit170(seeFIG.1). In contrast, the inactive air flow zone of the through-air apparatus may be defined as the area which does not include the web wrapped about the roll610.

The through-air roll610may rotate relative to another component, such as a stationary structure of the through-air apparatus. As set forth in more detail below, the stationary structure may include a variety of components, such as, but not limited to, an internal baffle, an inactive zone blocking plate, an exhaust duct, a plenum, and/or a hood radial or cross-machine stationary skirt. One of ordinary skill in the art would recognize that the stationary structure and its associated sealing elements may be made of various materials such as, but not limited to, Teflon, metal, and plastic. As set forth in more detail below, in one embodiment, the sealing elements are terminus locations and/or edges of the stationary structure.

The specific embodiment disclosed inFIGS.6-7illustrate a configuration where the stationary structure includes an inactive zone blocking plate630. As shown, the inactive blocking plate630is coupled to the baffle650and the plate630is configured to cover the inactive zone of the through-air roll610to prevent the in-leak of ambient air. As shown, the inactive blocking plate630may be a curved piece that matches the contour of the through-air roll610. In another embodiment, the blocking plate may be a flat piece.

In the embodiment shown inFIGS.6-7, the blocking plate630includes at least one sealing element. In this particular illustrative embodiment, there is a first sealing element632located at one end of the inactive zone, and a second sealing element634located at the other end of the inactive zone. One of ordinary skill in the art will recognize that the first and second sealing elements632,634are configured to reduce in-leak of ambient air into the active zone of the through-air apparatus, relative to an otherwise identical structure lacking the sealing elements. Furthermore, additional sealing elements (not shown) may also be provided around the circumference of the blocking plate630. As illustrated inFIGS.6-7, in one embodiment, the sealing elements632,634are terminus locations and/or edges of the blocking plate630. In another embodiment, the sealing elements may include other portions of the stationary structure, and it is also contemplated that the sealing elements may not be integrally formed with the stationary structure. As shown inFIG.6, and also as shown in the detailed view shown inFIG.7, one or more channels640are provided for the delivery of recirculated air, or other air stream, to at least one sealing element632,634thereby further reducing the in-leak of ambient air into the active zone of the through-air apparatus600. As shown, in one embodiment, the channel640is inside of the through-air roll610. As set forth below, in another embodiment, at least a portion of the channel640which is configured to direct air to one or more sealing elements may be positioned outside of the through-air roll610.

As shown inFIGS.6-7, at least one channel640extends radially outwardly from the first axis602towards a circumference of the through-air roll610. As shown, a first channel640extends outwardly towards the first sealing element632and a second channel640extends outwardly towards the second sealing element634. In another embodiment, one continuous channel640may be provided. In one embodiment, at least a portion of the channel640may extend along the first axis602(i.e. axis of rotation of the through-air roll610. It is contemplated that exhaust air, or some other system air from the through-air apparatus, may be circulated through the channel along the axis602and then radially out to the sealing elements632,634. As shown by the path of arrows inFIGS.6-7, the air may be directed radially outwardly towards the rotating through-air roll610. As shown, some of the air may also be directed substantially parallel to the inside surface of the blocking plate630, and may be configured to evenly distribute the air along the perimeter of the blocking plate630. The channels640may be designed with dampers, or other known flow controlling devices, to allow for even distribution of the recirculated air to the edge of the blocking plate sealing elements632,634.

The present disclosure also contemplates configurations where, for example, there are third and fourth sealing elements and one or more additional channels640extending out to the additional sealing elements to thereby further reduce the in-leak of ambient air into the active zone of the through-air apparatus. It should be appreciated that in one embodiment, the blocking plate630is rectangular shaped and has a sealing element associated with each of its four sides. One or more channels640may be configured to deliver the recirculated air, or other air stream to the sealing elements.

Another embodiment of a through-air apparatus is illustrated inFIGS.8-9. Some of the components inFIGS.8-9are similar to the components discussed above with respect to the embodiment shown inFIGS.6-7, and thus have identical reference numbers.FIGS.8-9illustrate a through-air apparatus700which includes a through-air roll610(i.e. rotating web-carrying structure) which is configured to rotate about a first axis602. As shown, a web620is wrapped around the roll610. The through-air roll610has a carrying surface612which has a plurality of openings to permit the passage of air. The apparatus700may also include rollers614which may assist in transfer of the web620onto and off of the roll610. The through-air roll610rotates relative to a stationary structure of the through-air apparatus. The specific embodiment disclosed inFIGS.8-9illustrate a configuration where the stationary structure includes an internal baffle750. Note that in this embodiment, there may or may not be an inactive zone blocking plate630, as described above and as shown inFIGS.6-7.

In the embodiment shown inFIGS.8-9, the baffle750includes at least a first baffle sealing element732and a second baffle sealing element734. In the illustrative embodiment, the first sealing element732is positioned at one end of the inactive zone and the second sealing element is positioned at the other end of the inactive zone. One of ordinary skill in the art will recognize that the first and second sealing elements732,734are configured to reduce in-leak of ambient air into the active zone of the through-air apparatus, relative to an otherwise identical baffle structure lacking the sealing elements. As shown inFIG.8, and also as shown in the detailed view shown inFIG.9, one or more channels740are provided for the delivery of recirculated air, or other air stream, to at least one sealing element732,734thereby further reducing the in-leak of ambient air into the active zone of the through-air apparatus700. As shown, in one embodiment, the channel740is inside of the through-air roll610. As shown inFIGS.8-9, at least one channel740extends radially outwardly from the first axis602towards a circumference of the through-air roll610. As shown, a first channel740extends outwardly towards the first sealing element732and a second channel740extends outwardly towards the second sealing element734. In one embodiment, at least a portion of the channel740may extend along the first axis602(i.e. axis of rotation of the through-air roll610). It is contemplated that exhaust air, or some other system air from the through-air apparatus, may be circulated through the channel along the axis602and then radially out to the sealing elements732,734.

As shown inFIGS.8-9, the sealing elements732,734may include at least one of a perforated plate, channel, nozzle, or slot configured to generate an air curtain to reduce the infiltration of ambient air into the through-air apparatus700. In this embodiment, the sealing elements732,734are configured to generate an air curtain extending radially outwardly toward the rotating through-air roll610. These features on the sealing elements732,734are represented inFIGS.8-9by the four parallel arrows extending outwardly from the sealing elements732,734toward the rotating through-air roll610. In other words, the sealing elements732,734may include channel segments742(i.e. channel portions) in gaseous communication with the one or more channels740for the delivery of recirculated air, or other air stream. As shown inFIGS.8-9, the channel segments742may have a rectangular cross-section and a perforated face744substantially parallel to the adjacent carrying surface612of the through-air roll610(i.e. rotating web-carrying structure). Air is delivered through these perforations746to further reduce the in-leak of ambient air into the active zone of the through-air apparatus700. Perforations746is intended to broadly include a perforated plate, channel, nozzle, slot, and/or other configurations known to one of ordinary skill in the art to generate an air curtain at the sealing element732,734. It should be appreciated that the perforations746may be profiled in the machine direction or the cross-machine direction to accommodate changing pressure or air flow requirements at various points along the sealing area. In other words, the perforations746may be oriented differently to achieve desirable effects. Furthermore, it should be appreciated that the disclosure contemplates one or more sealing elements732,734positioned along any side of the perimeter of the baffle750.

Turning now toFIG.10which illustrates a cross-sectional view of a though-air apparatus800according to another embodiment which includes a plenum810external to the through-air roll610. As discussed above, the through-air roll610(i.e. rotating web-carrying structure) is configured to rotate about its central axis. As shown, a web620is wrapped around the roll610and the apparatus800also include rollers614which assist in transfer of the web620onto and off of the roll610. In this specific embodiment shown inFIG.10, the through-air roll610rotates relative to a stationary structure of the through-air apparatus800which includes plenum810positioned to cover the inactive zone of the apparatus800. For simplicity, additional components of the through-air apparatus800inside of the through-air roll610are not shown inFIG.10. As represented by the plurality of arrows, the plenum includes one or more channels840for delivering recirculated air, or other air stream to the one or more plenum sealing elements832. In one embodiment, the sealed plenum810has a perforated plate844with a surface facing, in spaced apart relation, the exterior of the web carrying structure (i.e. through-air roll610) occupying the inactive zone of the through-air apparatus800. The sealed plenum810is in gaseous communication with one or more channels (such as channels640,740shown inFIGS.6-8) for the delivery of recirculated air, or other air streams, whereby the air is delivered through the perforated plate844to the inactive zone to further reduce the in-leak of ambient air into the active zone of the through-air apparatus800. As mentioned above, the term perforated plate844is intended to broadly include a perforated plate, channel, nozzle, slot, and/or other configurations known to one of ordinary skill in the art to generate an air curtain at the sealing element832. It should be appreciated that the perforations may be oriented in different configurations relative to the adjacent rotating through-air roll610to provide different air flow conditions along the sealing area.

FIGS.11-12illustrate one embodiment of a though-air apparatus900which includes a plurality of exhaust duct sealing elements932,934. In this embodiment, the through-air roll610rotates relative to one or more exhaust ducts910. An exhaust duct910is typically positioned at one end of the apparatus900and it is configured such that system air inside of the through-air roll610is drawn out of the apparatus900and then into the conduit/ducting170.FIG.11illustrates a cross-sectional side view of the through-air apparatus900with two exhaust duct sealing elements932,934positioned at one end of the apparatus900. In one embodiment, the exhaust duct sealing elements932,934may have a circular shape (i.e. donut-shaped). In another embodiment, these exhaust duct sealing elements932,934may have different geometries, and may for example include curved and/or straight portions. As shown, identical exhaust duct sealing element932,934may be positioned at the other end of the apparatus900. As mentioned above, there may be a space/gap between the rotating through-air roll610and the exhaust duct910. The exhaust duct sealing element932,934is configured to reduce the infiltration of ambient air into the through-air apparatus900.

For simplicity, additional components of the through-air apparatus900inside of the through-air roll610are not shown. The exhaust duct sealing elements932,934may be in gaseous communication with one or more channels for the delivery of air (from any of the above-described sources) to the exhaust duct sealing elements932,934to reduce the infiltration of ambient air into the through-air apparatus900. As represented by the arrows, there are one or more channels for delivering recirculated air, or other air stream to the one or more exhaust duct sealing elements932,934. It should be recognized that in this embodiment shown inFIGS.11-12, where the sealing elements932,934are external to the roll610, these channels may also be external to the roll610. This is in contrast to the channels640,740shown inFIGS.6-8which are internal to the roll.

It should be appreciated that the above-described perforations may also be provided on the exhaust duct sealing elements932,934to further reduce the in-leak of ambient air into the through-air apparatus900. As mentioned above, the term perforations is intended to broadly include a perforated plate, channel, nozzle, slot, and/or other configurations known to one of ordinary skill in the art to generate an air curtain at the sealing element932,934.

FIG.13is a cross-sectional side view of a through-air apparatus1000according to yet another embodiment of the present disclosure which includes a plurality of radial exhaust duct sealing elements932,934. In this embodiment, the through-air roll610rotates relative to one or more exhaust ducts910. Unlike the embodiment shown inFIG.11, in this embodiment, the end caps of the through-air roll610are closed. As shown, an exhaust duct910is typically positioned at one end of the apparatus1000and it is configured such that system air passes through the web-carrying structure (as represented by the arrows along the length of the through-air roll610) and is drawn out of the through-air roll610and into the exhaust duct910(represented by arrows adjacent the exhaust duct910) and then into the conduit/ducting170(as shown inFIGS.1-5).FIG.13illustrates two exhaust duct sealing elements932,934positioned at one end of the apparatus1000. In one embodiment, the radial exhaust duct sealing elements932,934may have a circular shape (i.e. donut-shaped), but as discussed above, other shapes and geometries are also contemplated. As mentioned above, there may be a space/gap between the rotating through-air roll610and the exhaust duct910. The radial exhaust duct sealing elements932,934are configured to reduce the infiltration of ambient air into the through-air apparatus1000.

For simplicity, additional components of the through-air apparatus1000inside of the through-air roll610are not shown. The radial exhaust duct sealing elements932,934may be in gaseous communication with one or more channels for the delivery of air (from any of the above-described sources) to the radial exhaust duct sealing elements932,934to reduce the infiltration of ambient air into the through-air apparatus1000. As represented by the arrows inside of the sealing elements932,934, there are one or more channels for delivering recirculated air, or other air stream to the one or more radial exhaust duct sealing elements932,934. It should be recognized that in this embodiment shown inFIG.13, where the sealing elements932,934are external to the roll610, these channels may also be external to the roll610.

The present disclosure also contemplates embodiments of a through-air apparatus that include a flow-through roll.FIG.14is a cross-sectional view of a through-air apparatus1100according to one embodiment which includes an outward flow-through arrangement, whereasFIG.15is a cross-sectional view of a through-air apparatus1200according to another embodiment which includes an inward flow-through arrangement.

The outward flow-through arrangement shown inFIG.14includes a though-air apparatus1100which includes a through-air roll610, an exhaust plenum1150, and a hood1130extending around the through-air roll610and the angular wrap of the web620. As discussed above, the through-air roll610(i.e. rotating web-carrying structure) is configured to rotate about its central axis. Similar to the embodiment disclosed inFIG.10, a web620is wrapped around the roll610and the apparatus1100also include rollers614which assist in transfer of the web620onto and off of the roll610. In this specific embodiment shown inFIG.14, the through-air roll610rotates relative to another structure of the through-air apparatus1100(which includes the stationary exhaust plenum1150, the rotating rollers614, and the hood1130). For simplicity, additional components of the through-air apparatus1100inside of the through-air roll610are not shown inFIG.14.

The path of system air is shown with open arrow heads inFIG.14. As shown, the system air extends down through the plenum1150positioned between the two rollers614and into the through-air roll610. Once inside the through-air roll610, the system air flows outwardly through the web-carrying structure of the through-air roll610.

As discussed above, the present disclosure is directed to including at least one channel which is configured to direct air to at least one sealing element on the through-air apparatus to reduce the infiltration of ambient air into the through-air apparatus. In this particular embodiment, the through-air apparatus1100includes exhaust plenum sealing elements1132positioned at the upper portion of the plenum1150adjacent the rollers614. The path of these channels which direct air to at least one sealing element is shown inFIG.14by the closed arrow heads. For example, as shown, there may be a channel inside of the exhaust plenum sealing elements1132to reduce the infiltration of ambient air into the through-air apparatus1100. As shown by the arrows, these channels may be angled toward roll614. In one embodiment, these channels run in the cross-machine direction. As shown inFIG.14, there may also be channels inside of the exhaust plenum1150and there may also be channels inside of the hood1130positioned around the periphery of the through-air roll610.

As represented by the plurality of closed arrow heads, the exhaust plenum1150and hood1130include one or more channels for delivering recirculated air, or other air stream to the one or more plenum sealing elements1132,1134. As discussed above, the exhaust plenum1150and hood1130are in gaseous communication with one or more channels for the delivery of recirculated air, or other air streams, whereby the air is delivered through the channels to reduce the in-leak of ambient air into the through-air apparatus1100. It should be recognized that in this embodiment shown inFIG.14, where the sealing elements1132,1134are external to the roll610, these channels may also be external to the roll610.

The inward flow-through arrangement shown inFIG.15includes a though-air apparatus1200which includes substantially the same labeled components described above with respect to the embodiment shown inFIG.14. The difference is that the direction of system air flow is opposite. In particular, the path of system air is shown with open arrow heads inFIG.15. As shown, the system air extends through the through-air roll610and upwardly into the exhaust plenum1150positioned between the rollers614. In some respects, the embodiment shown inFIG.15is similar to the plenum configuration shown inFIG.10.

InFIG.15, as represented by the plurality of closed arrow heads, the exhaust plenum1150includes one or more channels for delivering recirculated air, or other air stream to the one or more exhaust plenum sealing elements1132,1134. The exhaust plenum1150is in gaseous communication with one or more channels for the delivery of recirculated air, or other air streams, whereby the air is delivered through the channels to reduce the in-leak of ambient air into the through-air apparatus1200. It should be recognized that in this embodiment shown inFIG.15, where the sealing elements1132,1134are external to the roll610, these channels may also be external to the roll610. This is in contrast to the channels640,740shown inFIGS.6-8which are internal to the roll.

Turning now toFIG.16, which illustrates one embodiment of a through-air apparatus which includes a web-carrying structure that is configured for translational movement. In particular,FIG.16is a cross-sectional view of one embodiment of a through-air apparatus1300which includes a flatbed configuration, which may be configured as either a through-air dryer (TAD) or a through-air bonder (TAB). In summary, the principle is the same as the above described embodiment, the difference is that unlikeFIGS.6-15which are directed to a web-carrying structure which is configured as a through-air roll configured to rotate, the embodiment disclosed inFIG.16is directed to a web-carrying structure which is a flatbed belt1310. In one embodiment, the flatbed belt1310is a mesh/screen-like material that may be made from metal or synthetic strands. In the embodiment illustrated inFIG.16, the flatbed belt1310is configured for translational movement along a horizontal plane. In another embodiment, it is contemplated that the flatbed belt1310is configured for translational movement along an inclined plane. A web is placed on the flatbed belt1310and the flatbed belt1310is moved similar to a conveyor belt. As shown inFIG.16, adjacent components of the through-air apparatus1300, such as the upper plenum1330include at least one sealing element1332which is configured to reduce the infiltration of ambient air into the through-air apparatus1300. Furthermore, as represented by the arrows inFIG.16, at least one channel is provided which is configured to direct air to the at least one sealing element1332to reduce infiltration of ambient air into the through-air apparatus1300.

It should also be recognized that although many of the above-described through-air apparatus components with sealing elements may be discussed as being stationary relative to the moving web-carrying structure, the above-described concepts are also applicable to through-air apparatus components with sealing components that may be movable (configured for rotational and/or translational movement), as the disclosure is not limited in this respect. There may be in-leak of ambient air into the through-air apparatus with two movable components, thus the disclosure is directed to both stationary and movable components with sealing elements.

Furthermore, as discussed above, the through-air apparatus components with sealing elements may be positioned within the web-carrying structure (such as within through-air roll610, with the blocking plate sealing elements632,634and baffle sealing elements732,734shown inFIGS.6-9), and/or the through-air apparatus components with sealing elements may be positioned external to the web-carrying structure (such as outside of the through-air roll610, with the plenum sealing elements832and exhaust duct sealing elements932,934shown inFIGS.10-12).

Furthermore, one of ordinary skill in the art would recognize that in one embodiment, the above-described through-air apparatus may be used on a through-air dryer, and in another embodiment, the above-described through-air apparatus may be used on a through-air bonder, as the disclosure is not so limited.

Aspects of the present disclosure are directed to methods of operating a through-air apparatus. The method includes placing a web on a portion of a web-carrying structure and moving the web-carrying structure such that the web moves with the web-carrying structure. The method also includes providing a first component having at least one sealing element adjacent to the web-carrying structure, where the at least one sealing element on the first component is configured to reduce the infiltration of ambient air into the through-air apparatus, and directing air to the at least one sealing element to reduce the infiltration of ambient air into the through-air apparatus. In one embodiment, the act of directing air includes directing heated air to the at least one sealing element to reduce the infiltration of ambient air into the through-air apparatus. In another embodiment, a non-heated air stream may be directed to the at least one sealing element.

In one embodiment, the web-carrying structure is a through-air roll, and the method includes wrapping the web around an angular portion of a through-air roll, creating active and inactive air flow zones of the through-air apparatus, and rotating the through-air roll about a first axis such that the web rotates with the through-air roll. In another embodiment, the web-carrying structure is a flatbed belt configured for translational movement along either a horizontal or an inclined plane.

In one embodiment, the first component includes an exhaust duct and an exhaust duct sealing element and the air is directed to the exhaust duct sealing element to reduce the infiltration of ambient air into the through-air apparatus.

In another embodiment, the first component includes an internal baffle and an inactive zone blocking plate, and air is directed to the blocking plate sealing element to reduce the infiltration of ambient air into the through-air apparatus.

In yet another embodiment, the first component includes a plenum, and air is directed through the plenum to at least one sealing element to reduce the infiltration of ambient air into the through-air apparatus.

It should be understood that the present disclosure contemplates that there could also be second and third components of the through-air apparatus having additional sealing elements where air is directed to these additional sealing elements to reduce the infiltration of ambient air into the through-air apparatus.

It should also be recognized that, in one embodiment, the air directed to the one or more sealing elements may be recirculated system air from another portion of the through-air apparatus. In another embodiment, the air directed to the one or more sealing elements may be sources from at least one of a Yankee hot air system exhaust air stream, a vacuum pump exhaust air stream, a turbine exhaust air stream, or any other heated air stream. And in yet another embodiment, the air directed to the one or more sealing elements may be provided from a non-heated air source.

Furthermore, it should be recognized that the above-described concepts can be used to control and regulate humidity levels of the system air within the through-air apparatus.

Although several embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the functions and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the present invention. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto; the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, and/or methods, if such features, systems, articles, materials, and/or methods are not mutually inconsistent, is included within the scope of the present invention.

All references, patents and patent applications and publications that are cited or referred to in this application are incorporated in their entirety herein by reference.