Through-air device that reduces the intrusion of outside air

Abstract

A through-air device for drying or bonding a paper web, a tissue web, or a nonwoven web, and a method for operating the through-air device are provided. A through-air apparatus includes a first component including a web transport structure configured to move and at least one sealing element adjacent to the web transport structure, the sealing element configured to reduce ingress of ambient air into the through-air apparatus. The through-air apparatus further includes at least one flow path configured to direct air to the sealing element to reduce ingress of ambient air into the through-air apparatus. A method of operating the through-air apparatus includes directing air to the sealing element to reduce ingress of ambient air into the through-air apparatus.

Description

[Technical field]

[0001] The present invention relates, in part, to a through-air apparatus for producing a web product and a method of use for reducing ambient air infiltration into the through-air apparatus. [Background technology]

[0002] "Through-air technology" is a term used to describe systems and methods that allow air to be passed through papermaking webs, tissue webs, or nonwoven webs to dry or bond fibers or filaments. Examples include drying of nonwoven products (e.g., tea bags, specialty papers, etc.), drying and curing of fiberglass mats, filter papers, and resin-treated nonwovens, thermal bonding and drying of spunbond nonwovens, drying of hydroentangled webs, thermal bonding of bicomponent and non-bicomponent fiber-based geotextiles, drying and curing of interlining grades, and thermal bonding of absorbent cores with fusible binder fibers. Another application of through-air technology is drying of tissue.

[0003] Systems and methods related to through-air drying are commonly referred to using the acronym "TAD." Systems and methods related to through-air bonding are commonly referred to using the acronym "TAB."

[0004] Essentially, a through-air device comprises a rigid, air-permeable web transport structure onto which a web rests and onto which a fan blows air through the walls of the web transport structure while the web transport structure is moving, typically with a number of openings to allow air to pass through the structure. Summary of the Invention [Problem to be solved by the invention]

[0005] In a first aspect, a through-air apparatus for drying or bonding a papermaking web, tissue web, or nonwoven web is provided. [Means for solving the problem]

[0006] The apparatus includes a first component including a web transport structure configured to move and at least one sealing element adjacent to the web transport structure, the at least one sealing element configured to reduce intrusion of outside air into the through-air apparatus, and at least one flow path configured to direct air to the at least one sealing element to reduce intrusion of outside air into the through-air apparatus.

[0007] In another aspect, a method of operating a through-air apparatus for drying or bonding a papermaking, tissue or nonwoven web is provided. The method includes the steps of: placing a web on a portion of a web transport structure; and moving the web transport structure such that the web moves with the web transport structure. The method further includes providing a first component having at least one sealing element adjacent to the web transport structure, the at least one sealing element on the first component configured to reduce ingress of ambient air into the through-air apparatus. The method further includes directing air to the at least one sealing element to reduce ingress of ambient air into the through-air apparatus.

[0008] In yet another aspect, a through-air device for drying or bonding a papermaking, tissue or nonwoven web is provided. The device includes a rotating web transport structure having a transport surface with a plurality of openings to allow air to pass therethrough and a web wrap angle defining angular active and inactive zones of the web transport structure to form active and inactive airflow zones of the through-air device. The device further includes a stationary structure for relative rotation with the rotating web transport structure, the stationary structure including at least one sealing element configured to reduce in-leakage of outside air into the active zone of the through-air device compared to a comparable structure without the at least one sealing element. The device further includes at least one flow path for delivering recirculated air or other heated airflow to one or more of the sealing elements to further reduce in-leakage of outside air into the active zone of the through-air device. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a conventional through-air device system. [Diagram 2] FIG. 1 is a schematic diagram of a through-air equipment system according to one embodiment that recirculates air from within the equipment system. [Diagram 3] FIG. 13 is a schematic diagram of a through-air equipment system according to another embodiment, which recirculates air from within the equipment system. [Figure 4] FIG. 13 is a schematic diagram of a through-air equipment system according to another embodiment, which recirculates air from within the equipment system. [Diagram 5] FIG. 13 is a schematic diagram of a through-air device system according to yet another embodiment, which recirculates air from an external source. [Figure 6] FIG. 2 is a cross-sectional view of a through-air device according to one embodiment. [Figure 7] FIG. 7 is a detailed cross-sectional view of the circled portion in FIG. 6. [Figure 8] FIG. 4 is a cross-sectional view of a through-air device according to another embodiment. [Figure 9] FIG. 9 is a detailed cross-sectional view of the circled portion in FIG. 8. [Figure 10] FIG. 13 is a cross-sectional view of another embodiment of a through-air device having a plenum. [Figure 11] FIG. 13 is a side cross-sectional view of another embodiment of a through-air device having an exhaust duct sealing element. [Figure 12] FIG. 12 is a detailed cross-sectional view of the circled portion in FIG. 11. [Figure 13] FIG. 13 is a side cross-sectional view of another embodiment of a through-air device with a radial exhaust duct sealing element. [Figure 14] FIG. 13 is a cross-sectional view of a through-air device according to another embodiment having an outward flow-through arrangement. [Figure 15] FIG. 13 is a cross-sectional view of a through-air device according to another embodiment having an inward flow-through arrangement. [Figure 16] FIG. 13 is a cross-sectional view of a through-air device according to another embodiment having a flat bed configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present disclosure is directed to a through-air device configured to produce a variety of products, such as papermaking webs and / or tissue webs and / or nonwoven webs. Those skilled in the art will appreciate that the through-air device can be configured as a through-air dryer (TAD) and / or a through-air bonder (TAB) depending on the application in which the device is used. Those skilled in the art will appreciate that the through-air device can be used to produce a variety of web products in the form of a finished end product in roll form. Those skilled in the art will appreciate that the product does not have to be in roll form and / or can be cut into a finished end product. Those skilled in the art will appreciate that the through-air device can be configured to produce a variety of products, such as, but not limited to, films, fabrics or other web-type materials, and can be used in a variety of processes, such as, but not limited to, material transfer, heat transfer, material displacement, web handling, and quality monitoring, including, but not limited to, drying, heat bonding, sheet transport, water extraction, web tensioning, porosity measurement, and the like.

[0011] As described in more detail below, the through-air device includes a rigid, air-permeable web transport structure configured to move relative to other parts of the device. A web may be placed on the web transport structure and processed by a fan blowing air through the walls of the web transport structure as the web moves. Typically, the web transport structure has a number of openings to allow the air to pass through the structure. As described in more detail below and shown in Figures 6-15, in some embodiments, the web transport structure is a through-air roll configured for rotational motion about a first axis. As described in more detail below and shown in Figure 16, in other embodiments, the web transport structure is a flat bed belt configured for translational motion along a horizontal or inclined surface. It should be understood that the disclosure is not limited in this respect and that each of the configurations described below may be incorporated into a wide variety of through-air device configurations that utilize web transport structures configured for rotational and / or translational motion.

[0012] In a particular embodiment, the web (i.e., the product), typically in the form of a sheet, is partially wrapped around the cylindrical shell (i.e., through-air roll) of the through-air device. The web is wrapped around a portion of the roll, for example, between 90° and 360°, typically between 180° and 300°. Typically, the cylindrical wall of the through-air roll has a number of openings configured to allow air to pass through. A fan / blower directs air over the product. Typically, the through-air roll is located in a hood that optimizes airflow characteristics. The fan / blower directs air through the cylindrical shell wall to treat the product as it moves with the rotating shell and passes through the active zone of the device. A heater may be provided to allow heated air to flow through the through-air roll.

[0013] FIG. 1 illustrates a conventional through-air device system. As shown, the through-air device 100 includes a through-air roll 120 configured to rotate within a hood 130. The system includes a main fan 140 that directs system air (also known as process air) into the hood 130 via a conduit 170 and draws the air through the through-air roll 120. As shown, an air heater 150 may also be connected to the conduit 170, which directs heated air to the through-air roll 120. The system may further include an exhaust fan 160 that draws air from the device 100 via the conduit 170 and expels it to the outside air. As shown in FIG. 1, the system air is a closed loop, where the system air flows from the main fan 140 through the conduit 170 into the hood 130, passes through the through-air roll 120, and exits through an exhaust duct or flows into the conduit 170.

[0014] Typically, the through-air device 100 is a very large machine. For example, the through-air roll 120 may be 1 foot (about 0.30 m) to 30 feet (about 9.14 m) in length and 1 foot (about 0.30 m) to 22 feet (about 6.71 m) in diameter. The cylindrical walls of the roll 120 may be made of a rigid structure with openings to allow air to flow through. In one embodiment, the through-air roll 120 may be a HONEYCOMBROLL® manufactured by Valmet Corporation.

[0015] As previously discussed, the through-air apparatus 100 has an active airflow zone configured to receive the system air and treat the web. As shown in FIG. 1, the active airflow zone is formed in part by a portion of the through-air roll 120 configured to receive the web product. Also shown in FIG. 1, the through-air apparatus further has an inactive airflow zone formed in part by a portion of the through-air roll 120 not configured to receive the web product. As will be described in more detail below, the active and inactive zones may vary depending on how the web is wrapped around the through-air roll 120.

[0016] The inventors of the present invention have found that the conventional through-air device 100 shown in FIG. 1 has problems. Specifically, the inventors have found that the through-air device 100 allows undesirable in-leakage of outside air. As will be described in more detail below, typically there is a space, or gap, between the web transport structure and adjacent components of the through-air device 100 to allow movement of the web transport structure. Typically, this gap is about 0.06 to 0.375 inches. In this particular embodiment shown in FIG. 1, the web transport structure is a rotating through-air roll 120. To reduce in-leakage of outside air, these adjacent components may be provided with at least one sealing element (described below). However, intrusion of outside air into the through-air device still occurs at these locations. The inventors have found that there is currently a limit to how small the seal clearance can be set due to various factors such as the size, width, operating vacuum, rotational speed, and load of the through-air roll. As will be described in more detail below, aspects of the present disclosure are directed to reducing and controlling such inleakage of outside air into the through-air device.

[0017] As described in more detail below, aspects of the present disclosure include directing air to at least one sealing element of one or more components of the through-air device to reduce intrusion of outside air into the through-air device. As described below, the air directed to the sealing element may originate from a variety of sources, including, but not limited to, recirculating system air from another portion of the through-air device system. In one embodiment, the air originates from an exhaust line of the through-air device. Other air sources are contemplated and are described below. For example, either a heated or unheated air source not specifically present in the through-air device system may be used. As described below, the through-air device is provided with at least one flow path that directs the air to the sealing element.

[0018] The inventors believe that the present disclosure may provide various advantages. First, the concepts of the present disclosure may be utilized to increase the energy efficiency of the through-air device by recycling exhaust air and / or minimizing internal heat loss and / or reducing outside air intrusion into the device. Second, the concepts described herein may be utilized to facilitate regulation and / or control of the humidity level of the system air within the through-air device. Third, the concepts of the present disclosure may allow for a larger gap / space between the sealing element and the web transport structure compared to conventional through-air devices.

[0019] Various embodiments will be described in detail below, but before that, the entirety of the schematic diagrams of various through-air devices devised by the inventors shown in Figs. 2 to 5 will be described.

[0020] The inventors have developed a novel through-air device configuration that reduces the ingress of outside air into the through-air device. As will be described in more detail below, the device includes at least one flow path that delivers air to at least one sealing element. Figures 2-5 are various schematic diagrams of a through-air device system, illustrating various sources of air contemplated in the present disclosure. Figures 6-16 (described below) show various configurations for the flow paths within the through-air device that direct the air to the sealing element.

[0021] FIG. 2 is a schematic diagram of an embodiment of a through-air device system in which heated air is delivered to at least one sealing element by a booster fan 204. Similar to FIG. 1, the through-air device 200 includes a through-air roll 120 configured to rotate within a hood 130. As shown, in one embodiment, the web transport structure is a through-air roll 120. As will be described in more detail below, and as shown in FIG. 16, in other embodiments, the web transport structure may comprise a flat bed belt configured for translational motion, in which case the web transport structure may comprise a flat bed belt configured for translational motion. As shown, a main fan 140 directs system air into the through-air device 200 via a conduit 170. An air heater 150 may be used to direct heated air into the through-air device 200. Additionally, an exhaust fan 160 may be used to draw air out of the device 200.

[0022] Notably, unlike the conventional device shown in FIG. 1, the through-air device 200 shown in FIG. 2 includes an additional conduit 202 with a booster fan 204. As will be described in more detail below, the conduit 202 and the booster fan 204 are configured to direct air to at least one sealing element in the through-air device 200. Details of how the air is directed to the sealing element are shown in FIGS. 6-16 and will be described in more detail below. As shown in FIG. 2, the conduit 202 and the booster fan 204 are used to specifically direct the exhaust air from the conduit 170 back to the at least one sealing element in the through-air device 200, thereby reducing the intrusion of outside air into the through-air device 200.

[0023] FIG. 3 is a schematic system diagram of another embodiment of the through-air device 300. FIG. 3 differs from FIG. 2 in that the embodiment of FIG. 3 uses a conduit 302 instead of the conduit 202 and booster fan 204 shown in FIG. 2, which recirculates the heated exhaust air to the sealing element in the through-air device 300. As mentioned above, the details of how the air can be specifically directed to the sealing element are shown in FIGS. 6-16 and will be described in detail later. In this embodiment, the conduit 302 is located downstream of the exhaust fan 160, which allows the exhaust fan 160 to direct the air to the sealing element. That is, in this particular embodiment, a separate booster fan 204 is not required.

[0024] The present disclosure also contemplates that the air directed to the sealing element may be delivered from a source other than the exhaust line. For example, the present disclosure contemplates that, in one embodiment, the main fan 140 directs and delivers air to the sealing element, as described in the system schematic diagram of FIG. 4. As shown, a conduit 402 is provided that branches off from the normal conduit 170 between the main fan 140 and the air heater 150. As will be described in more detail below, the conduit 402 is configured to direct air to at least one sealing element of the through-air device 400. As will be described in more detail below, the conduit 402 may also include one or more flow control structures, such as a damper 404, that control the amount of air flowing to the sealing element. This may allow for the humidity level of the system air to be controlled / adjusted.

[0025] 5 is a schematic diagram of another through-air device system according to yet another embodiment. In this embodiment, air is delivered to the sealing element from a heated air source 510 that is external to the system air of the through-air device system. The disclosure is not so limited and non-heated heat sources are also contemplated. As shown, the conduit 502 is configured to direct heated air from the heated air source 510 to the sealing element of the through-air device 500. For example, in one embodiment, the air source 510 can include pre-heated outside air, turbine exhaust, Yankee hot air system exhaust, vacuum pump exhaust, other heated air flow in a paper machine or paper mill environment, or any other heated air source. The disclosure is not so limited and other embodiments may include non-heated air sources.

[0026] As shown in Figures 2-5, the present disclosure contemplates various configurations for obtaining air from various sources (either internal to the through-air device system or from an external source external to the system air of the through-air device system) and directing the air into the through-air device and toward at least one sealing element.

[0027] Next, with reference to Figures 6 to 16, details of how the air can specifically be directed to the at least one sealing element of the through-air device will be explained in detail.

[0028] FIG. 6 shows a through-air device 600 including a through-air roll 610 (i.e., a rotating web transport structure) configured to rotate about a first axis 602. As shown, the roll 610 has a web 620 wrapped around it. The through-air roll 610 has a transport surface 612 with a plurality of openings to allow air to pass through. The device 600 may further include rollers 614 that may assist in transferring the web 620 onto and off the roll 610. A web wrap angle θ defines angular active and inactive zones of the web transport structure. As shown in FIG. 6, the rollers 614 are positioned such that the web wrap angle θ of the inactive zone is about 110°, i.e., the web angle of the active zone is about 250°. It will be apparent to one skilled in the art that the disclosure is not limited thereto and that the angles may be different.

[0029] It will also be apparent to one skilled in the art that the inactive and active zones of the web transport structure define corresponding active and inactive airflow zones of the through-air apparatus. As previously discussed, the active airflow zone of the through-air apparatus is the portion configured to receive the system air and process the web. The active airflow zone of the through-air apparatus may be defined as the area where the web is wrapped around roll 610 and the surrounding area configured to receive system air from conduit 170 (see FIG. 1). In contrast, the inactive airflow zone of the through-air apparatus may be defined as the area where the web is not wrapped around roll 610.

[0030] The through-air roll 610 may rotate relative to another component of the through-air device, such as a stationary structure. As will be described in more detail below, the stationary structure may include various components such as, but not limited to, an internal baffle and / or an inactive zone blocking plate and / or an exhaust duct and / or a plenum and / or a stationary radial or cross machine skirt of a hood. Those skilled in the art will appreciate that the stationary structure and associated sealing elements may be made of various materials, such as, but not limited to, Teflon, metal, plastic, etc. In one embodiment, the sealing elements are at the ends and / or edges of the stationary structure, as will be described in more detail below.

[0031] The particular embodiment disclosed in Figures 6 and 7 illustrates a configuration in which the stationary structure comprises a non-active zone blocking plate 630. As shown, the non-active zone blocking plate 630 is coupled to a baffle 650. The plate 630 is configured to cover the non-active zone of the through air roll 610 to prevent in-leakage of outside air. As shown, the non-active zone blocking plate 630 can be a curved member that matches the contour of the through air roll 610. In other embodiments, the blocking plate can be a flat member.

[0032] In the embodiment shown in Figures 6 and 7, the blocking plate 630 includes at least one sealing element. In this particular exemplary embodiment, there is a first sealing element 632 located at one end of the inactive zone and a second sealing element 634 located at the other end of the inactive zone. It will be apparent to one skilled in the art that the first and second sealing elements 632, 634 are configured to reduce leakage of outside air into the active zone of the through-air device compared to a comparable structure without the sealing elements. An additional sealing element (not shown) may also be provided on the periphery of the blocking plate 630. As shown in Figures 6 and 7, in one embodiment, the sealing elements 632, 634 are at the ends and / or edges of the blocking plate 630. In other embodiments, the sealing elements may include separate portions of the fixed structure and may not be integrally formed with the fixed structure. As shown in Figure 6 and as detailed in Figure 7, at least one flow channel 640 is provided to deliver recirculated or other airflow to at least one sealing element 632, 634 to further reduce in-leakage of ambient air into the active zone of the through-air apparatus 600. As shown, in one embodiment, the flow channel 640 is internal to the through-air roll 610. As will be described later, in other embodiments, at least a portion of the flow channel 640 configured to direct air to the at least one sealing element may be external to the through-air roll 610.

[0033] As shown in Figures 6 and 7, at least one flow passage 640 extends radially outward from the first axis 602 toward the outer circumference of the through-air roll 610. As shown, the first flow passage 640 extends outward toward the first sealing element 632, and the second flow passage 640 extends outward toward the second sealing element 634. In other embodiments, a single continuous flow passage 640 may be provided. In one embodiment, at least a portion of the flow passage 640 may extend along the first axis 602 (i.e., the axis of rotation of the through-air roll 610). It is contemplated that exhaust air or any other system air from the through-air device may flow along the axis 602 in the flow passage and then exit radially to the sealing elements 632, 634. The air may be directed radially outward toward the rotating through-air roll 610, as shown by the arrows in Figures 6 and 7. Also, as shown, a portion of the air may be directed generally parallel to the inner surface of the blocking plate 630 to create an even distribution of air along the periphery of the blocking plate 630. The flow passages 640 may be configured with dampers or other known flow control devices to evenly distribute the recirculated air to the edges of the blocking plate sealing elements 632, 634.

[0034] The present disclosure contemplates, for example, a third and fourth sealing element and at least one additional flow passage 640 extending outwardly toward the additional sealing elements to further reduce in-leakage of outside air into the active zone of the through-air device. In one embodiment, the blocking plate 630 is rectangular with a sealing element on each of its four sides. At least one flow passage 640 may be configured to deliver recirculated air or other airflow to the sealing elements.

[0035] Another embodiment of a through-air device is shown in Figures 8 and 9. Some components of Figures 8 and 9 are similar to those previously described in connection with the embodiment shown in Figures 6 and 7 and are therefore numbered the same.

[0036] 8 and 9 show a through-air apparatus 700 including a through-air roll 610 (i.e., a rotating web transport structure) configured to rotate about a first axis 602. As shown, the roll 610 has a web 620 wrapped around it. The through-air roll 610 has a transport surface 612 with a number of openings to allow air to pass through. The apparatus 700 may further include rollers 614 that may assist in transporting the web 620 onto and off of the roll 610. The through-air roll 610 rotates relative to a stationary structure of the through-air apparatus. The particular embodiment disclosed in FIGS. 8 and 9 shows the stationary structure as an internal baffle 750. It is noted that in this embodiment, the non-active zone blocking plate 630 may or may not be present, as described above and shown in FIGS. 6 and 7.

[0037] In the embodiment shown in Figures 8 and 9, the baffle 750 comprises at least a first baffle sealing element 732 and a second baffle sealing element 734. In this exemplary embodiment, the first sealing element 732 is located at one end of the inactive zone and the second sealing element is located at the other end of the inactive zone. Those skilled in the art will appreciate that the first and second sealing elements 732, 734 are configured to reduce in-leakage of outside air into the active zone of the through-air device as compared to a comparable baffle structure without the sealing elements. As shown in Figure 8 and as detailed in Figure 9, at least one flow passage 740 is provided to deliver recirculated air or other airflow to at least one sealing element 732, 734 to further reduce in-leakage of outside air into the active zone of the through-air device 700. As shown, in one embodiment, the flow passage 740 is internal to the through-air roll 610. As shown in Figures 8 and 9, at least one flow passage 740 extends radially outward from the first axis 602 toward the outer circumference of the through-air roll 610. As shown, the first flow passage 740 extends outward toward the first sealing element 732, and the second flow passage 740 extends outward toward the second sealing element 734. In one embodiment, at least a portion of the flow passage 740 may extend along the first axis 602 (i.e., the axis of rotation of the through-air roll 610). It is contemplated that exhaust air or any other system air from the through-air device may flow along the axis 602 in the flow passage and then exit radially to the sealing elements 732, 734.

[0038] As shown in Figures 8 and 9, the sealing elements 732, 734 may include at least one of a perforated plate, a channel, a nozzle, and a slot configured to generate an air curtain to reduce intrusion of outside air into the through-air device 700. In this embodiment, the sealing elements 732, 734 are configured to generate an air curtain that extends radially outward toward the rotary through-air roll 610. In Figures 8 and 9, such functionality of the sealing elements 732, 734 is represented by four parallel arrows extending outward from the sealing elements 732, 734 toward the rotary through-air roll 610. That is, the sealing elements 732, 734 may include a channel segment 742 (i.e., a channel portion) in gas communication with at least one channel 740 that delivers recirculated air or other airflow. As shown in Figures 8 and 9, the channel segment 742 may have a rectangular cross section and a perforated surface 744 that is generally parallel to the adjacent conveying surface 612 of the through-air roll 610 (i.e., the rotating web conveying structure). Air is forced through such perforations 746 to further reduce in-leakage of outside air into the active zone of the through-air device 700. Perforations 746 are intended to broadly encompass perforated plates and / or channels and / or nozzles and / or slots and / or other configurations that would be understood by one skilled in the art to create an air curtain at the sealing elements 732, 734. It should be understood that perforations 746 can be configured in a variety of machine direction or cross machine direction configurations to meet various pressure and air flow needs along the sealing area. That is, perforations 746 can be oriented in a variety of ways to achieve a desired effect. The present disclosure also contemplates disposing at least one sealing element 732, 734 along any side of the perimeter of the baffle 750.

[0039] Reference is now made to FIG. 10, which is a cross-sectional view of a through-air device 800 according to another embodiment. The through-air device 800 includes a plenum 810 that is external to the through-air roll 610. As previously described, the through-air roll 610 (i.e., the rotating web transport structure) is configured to rotate about a central axis. As shown, the roll 610 has a web 620 wound thereon. The device 800 further includes rollers 614 that aid in the transfer of the web 620 onto and off the roll 610. In this particular embodiment shown in FIG. 10, the through-air roll 610 rotates relative to a stationary structure of the through-air device 800. The through-air device 800 includes a plenum 810 that is positioned to cover an inactive zone of the device 800. Other components of the through-air device 800 that are internal to the through-air roll 610 are omitted from FIG. 10 for simplicity. The plenum has at least one flow passage 840 for delivering recirculated or other airflow to at least one plenum sealing element 832, as represented by multiple arrows. In one embodiment, a perforated plate 844 of the sealed plenum 810 has a surface facing an outer portion of the web-transporting structure (i.e., through-air roll 610) that occupies the inactive zone of the through-air device 800 at a spaced distance. The sealed plenum 810 is in gas communication with at least one flow passage for delivering recirculated or other airflow (e.g., flow passages 640, 740, etc., shown in Figures 6-8), which delivers air through the perforated plate 844 to the inactive zone, thereby further reducing in-leakage of outside air into the active zone of the through-air device 800. As previously mentioned, the term perforated plate 746 is intended to broadly encompass perforated plates and / or flow passages and / or nozzles and / or slots and / or other configurations that one skilled in the art would understand would generate an air curtain at the sealing element 832. It should be appreciated that by varying the orientation of the perforations relative to the adjacent rotating through air roll 610, different air flow conditions can be established along the sealed area.

[0040] 11 and 12 show an embodiment of the through-air device 900. The through-air device 900 includes a plurality of exhaust duct sealing elements 932, 934. In this embodiment, the through-air roll 610 rotates relative to at least one exhaust duct 910. Typically, the exhaust duct 910 is located at one end of the device 900, and the system air inside the through-air roll 610 is drawn out of the device 900 and into the conduit / duct 170. FIG. 11 shows a side cross-sectional view of the through-air device 900 with two exhaust duct sealing elements 932, 934 located at one end. In one embodiment, the exhaust duct sealing elements 932, 934 can be circular (i.e., donut-shaped). In other embodiments, the exhaust duct sealing elements 932, 934 can be of other geometric shapes, for example, they can include curved and / or straight sections. As shown, the other end of the apparatus 900 may be provided with identical exhaust duct sealing elements 932, 934. As previously mentioned, there may be a space / gap between the rotating through-air roll 610 and the exhaust duct 910. The exhaust duct sealing elements 932, 934 are configured to reduce ingress of outside air into the through-air apparatus 900.

[0041] For simplicity, other components of the through-air device 900 that are internal to the through-air roll 610 are not shown. The exhaust duct sealing elements 932, 934 may be in gas communication with at least one flow path that delivers air (from any of the sources mentioned above) to the exhaust duct sealing elements 932, 934 to reduce intrusion of outside air into the through-air device 900. As represented by the arrows, there is at least one flow path that delivers recirculated air or other airflow to the at least one exhaust duct sealing element 932, 934. It will be apparent that in the present embodiment shown in Figures 11 and 12 where the sealing elements 932, 934 are external to the roll 610, the flow paths may also be external to the roll 610. This is in contrast to the flow paths 640, 740 of Figures 6-8, which are internal to the roll.

[0042] It will also be appreciated that providing the exhaust duct sealing elements 932, 934 with the aforementioned perforations may further reduce in-leakage of outside air into the through-air device 900. As previously mentioned, the term perforations is intended to broadly encompass perforated plates and / or channels and / or nozzles and / or slots and / or other configurations that would be understood by one of ordinary skill in the art to create an air curtain in the sealing elements 932, 934.

[0043] FIG. 13 is a side cross-sectional view of a through-air device 1000 according to yet another embodiment of the present disclosure. The through-air device 1000 includes a plurality of radial exhaust duct sealing elements 932, 934. In this embodiment, the through-air roll 610 rotates relative to at least one exhaust duct 910. Unlike the embodiment shown in FIG. 11, in this embodiment, the end caps of the through-air roll 610 are closed. As shown, the exhaust duct 910 is typically located at one end of the device 1000, and is configured such that system air passes through the web transport structure (as represented by the arrows along the length of the through-air roll 610), is drawn from the through-air roll 610 into the exhaust duct 910 (as represented by the arrows on the side of the exhaust duct 910), and is drawn into the conduit / duct 170 (shown in FIGS. 1-5). FIG. 13 illustrates two exhaust duct sealing elements 932, 934 located at one end of the device 1000. In one embodiment, the radial exhaust duct sealing elements 932, 934 may be circular (i.e., donut shaped), although as previously mentioned other shapes and geometries are contemplated. As previously mentioned, there may be a space / gap between the rotating through-air roll 610 and the exhaust duct 910. The radial exhaust duct sealing elements 932, 934 are configured to reduce ingress of outside air into the through-air device 1000.

[0044] For simplicity, other components of the through-air device 1000 that are internal to the through-air roll 610 are not shown. The radial exhaust duct sealing elements 932, 934 may be in gas communication with at least one flow path that delivers air (from any of the sources mentioned above) to the radial exhaust duct sealing elements 932, 934 to reduce intrusion of outside air into the through-air device 1000. As represented by the arrows inside the sealing elements 932, 934, there is at least one flow path that delivers recirculated air or other airflow to the at least one radial exhaust duct sealing element 932, 934. It will be apparent that in the present embodiment shown in FIG. 13 where the sealing elements 932, 934 are external to the roll 610, the flow paths may also be external to the roll 610.

[0045] The present disclosure also contemplates embodiments of through-air devices with flow-through rolls: Figure 14 is a cross-sectional view of one embodiment of a through-air device 1100 in an outward flow-through configuration, and Figure 15 is a cross-sectional view of another embodiment of a through-air device 1200 in an inward flow-through configuration.

[0046] The outward flow-through arrangement shown in FIG. 14 includes a through-air device 1100. The through-air device 1100 includes a through-air roll 610, an exhaust plenum 1150, and a hood 1130 that extends around the angular wrap of the web 620 and the through-air roll 610. As previously described, the through-air roll 610 (i.e., a rotating web transport structure) is configured to rotate about a central axis. Similar to the embodiment disclosed in FIG. 10, the web 620 is wrapped around the roll 610. The device 1100 further includes rollers 614 that aid in the transport of the web 620 onto and off the roll 610. In this particular embodiment shown in FIG. 14, the through-air roll 610 rotates relative to other structures (e.g., the fixed exhaust plenum 1150, the rotating rollers 614, the hood 1130) of the through-air device 1100. For simplicity, other components of the through-air device 1100 that are inside the through-air roll 610 are omitted from FIG.

[0047] The path of the system air is shown with open arrow heads in Figure 14. As shown, the system air travels downward through a plenum 1150 located between two rollers 614 and into the through air roll 610. Once inside the through air roll 610, the system air flows outwardly through the web transport structure of the through air roll 610.

[0048] As mentioned above, the present disclosure is directed to at least one flow channel configured to direct air to at least one sealing element of the through-air device to reduce intrusion of outside air into the through-air device. In this particular embodiment, the through-air device 1100 includes an exhaust plenum sealing element 1132 disposed at the top of the plenum 1150 adjacent to the roller 614. In FIG. 14, the paths of these flow channels directing air to the at least one sealing element are shown with closed arrow heads. As shown, for example, there may be flow channels inside the exhaust plenum sealing element 1132 to reduce intrusion of outside air into the through-air device 1100. Such flow channels may be angled toward the roll 614 as shown by the arrows. In one embodiment, such flow channels extend in the cross machine direction. As shown in FIG. 14, there may be flow channels inside the exhaust plenum 1150 as well as inside the hood 1130 located on the periphery of the through-air roll 610.

[0049] As represented by the multiple sharp arrows, the exhaust plenum 1150 and hood 1130 have at least one flow passage for delivering recirculated air or other airflow to at least one plenum sealing element 1132, 1134. As previously mentioned, the exhaust plenum 1150 and hood 1130 are in gas communication with at least one flow passage for delivering recirculated air or other airflow through which air is directed to reduce in-leakage of outside air into the through-air device 1100. It will be apparent that in the embodiment shown in FIG. 14 where the sealing elements 1132, 1134 are external to the roll 610, the flow passages may also be external to the roll 610.

[0050] The inward flow-through arrangement shown in Figure 15 includes a through-air device 1200. The through-air device 1200 includes substantially the same (numbered) components as previously described in connection with the embodiment shown in Figure 14. The difference is that the flow direction of the system air is reversed. Specifically, in Figure 15, the path of the system air is shown by an open arrow. As shown, the system air travels upward through the through-air roll 610 into an exhaust plenum 1150 located between the rollers 614. The embodiment shown in Figure 15 has some similarities to the plenum configuration shown in Figure 10.

[0051] In FIG. 15, the exhaust plenum 1150 has at least one flow path for delivering recirculated air or other airflow to at least one exhaust plenum sealing element 1132, 1134, as represented by the multiple sharp arrows. The exhaust plenum 1150 is in gas communication with at least one flow path for delivering recirculated air or other airflow through which air is directed to reduce in-leakage of outside air into the through-air device 1200. It will be apparent that in the embodiment shown in FIG. 15 where the sealing elements 1132, 1134 are external to the roll 610, the flow paths may also be external to the roll 610. This is in contrast to the flow paths 640, 740 of FIGS. 6-8, which are internal to the roll.

[0052] Reference is now made to FIG. 16, which depicts an embodiment of a through-air device with a web transport structure configured for translational motion. Specifically, FIG. 16 is a cross-sectional view of an embodiment of a through-air device 1300 with a flatbed configuration that may be configured as a through-air dryer (TAD) or a through-air bonder (TAB). In summary, the principle itself is the same as the previously described embodiments, but unlike FIGS. 6-15, which are directed to a web transport structure configured as a through-air roll configured to rotate, the embodiment disclosed in FIG. 16 is directed to a web transport structure that is a flatbed belt 1310. In one embodiment, the flatbed belt 1310 is a mesh / screen-like material that may be made of metal or synthetic strands. In the embodiment shown in FIG. 16, the flatbed belt 1310 is configured for translational motion along a horizontal plane. In other embodiments, it is also conceivable that the flatbed belt 1310 is configured for translational motion along an inclined plane. The web is placed on the flatbed belt 1310, which is moved like a conveyor belt. As shown in Figure 16, adjacent components of the through-air device 1300, such as the upper plenum 1330, include at least one sealing element 1332 configured to reduce intrusion of outside air into the through-air device 1300. Additionally, at least one flow path, represented by arrows in Figure 16, is provided and configured to direct air to the at least one sealing element 1332 to reduce intrusion of outside air into the through-air device 1300.

[0053] Additionally, while many of the components of the through-air devices described herein that are described as having sealing elements may be described as being stationary relative to a moving web-transporting structure, it will be apparent that the present disclosure is not so limited and the concepts described above are also applicable to components of the through-air devices that have sealing parts and that may be movable (configured for rotational and / or translational movement). Since in-leakage of outside air may occur even in through-air devices in which two components are movable relative to each other, the present disclosure is directed to both stationary and movable components having sealing elements.

[0054] Also, as described above, components of the through-air device having sealing elements may be located inside the web transport structure (e.g., the blocking plate sealing elements 632, 634 and baffle sealing elements 732, 734 shown in Figures 6-9, which are inside the through-air roll 610) and / or components of the through-air device having sealing elements may be located outside the web transport structure (e.g., the plenum sealing element 832 and exhaust duct sealing elements 932, 934 shown in Figures 10-12, which are outside the through-air roll 610).

[0055] In addition, it will be apparent to those skilled in the art that, as one embodiment, the above-mentioned through-air device may be applied to a through-air drying device, and as another embodiment, the above-mentioned through-air device may be applied to a through-air bonding device, since there is no such limitation in the present disclosure.

[0056] Aspects of the present disclosure are directed to a method of operating a through-air device. The method includes the steps of: placing a web on a portion of a web transport structure; and moving the web transport structure so that the web moves with the web transport structure. The method further includes the steps of providing a first component having at least one sealing element adjacent to the web transport structure, the at least one sealing element of the first component configured to reduce intrusion of outside air into the through-air device; and directing air to the at least one sealing element to reduce intrusion of outside air into the through-air device. In one embodiment, the step of directing air includes directing heated air to the at least one sealing element to reduce intrusion of outside air into the through-air device. In other embodiments, a flow of unheated air can be directed to the at least one sealing element.

[0057] In one embodiment, the web transport structure is a through-air roll and the method includes wrapping the web around angular portions of the through-air roll to form active and inactive airflow zones of the through-air device, 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 transport structure is a flat bed belt configured for translational motion along a horizontal or inclined surface.

[0058] In one embodiment, the first component includes an exhaust duct and an exhaust duct sealing element, the air being directed to the exhaust duct sealing element to reduce intrusion of outside air into the through-air device.

[0059] In another embodiment, the first component includes an internal baffle and a non-active zone blocking plate, and air is directed to the blocking plate sealing element to reduce intrusion of outside air into the through-air device.

[0060] 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 intrusion of outside air into the through-air device.

[0061] It should be understood that the present disclosure also contemplates a configuration in which the through-air device may have second and third components with additional sealing elements, and air is directed to these additional sealing elements to reduce intrusion of outside air into the through-air device.

[0062] It will also be apparent that in one embodiment, the air directed to the at least one sealing element may be system air recirculated from another portion of the through-air device. In other embodiments, the air directed to the at least one sealing element may be sourced from at least one of a Yankee hot air system exhaust stream, a vacuum pump exhaust stream, a turbine exhaust stream, and any other heated air stream. In yet other embodiments, the air directed to the at least one sealing element may be sourced from an unheated air source.

[0063] It will also be apparent that the above concepts may be utilized to control and regulate the humidity level of the system air within the through-air device.

[0064] While several embodiments of the invention have been shown and described herein, those skilled in the art will readily envision various other means and / or structures for obtaining the functions described herein and / or the results and / or one or more advantages described herein. Such variations and / or modifications are deemed to be within the scope of the present invention. Many equivalents to the specific embodiments of the invention described herein will be apparent to, or can be determined with no more than routine experimentation by, those skilled in the art. It is therefore to be understood that the above-described embodiments are presented by way of example only, and that within the scope of the appended claims and equivalents thereof, the invention may be practiced otherwise than as claimed and specifically described. The present invention is directed to each individual configuration and / or system and / or article and / or material and / or method described herein. Also, any combination of two or more such configurations and / or systems and / or articles and / or materials and / or methods is within the scope of the present invention, provided such configurations and / or systems and / or articles and / or materials and / or methods are not mutually inconsistent.

[0065] All definitions set forth and employed herein are to be understood to supersede any dictionary definitions and / or definitions in any documents incorporated by reference and / or ordinary meaning of each defined term.

[0066] The indefinite articles "a" and "an," as used in the specification and claims, unless otherwise indicated, should be understood to mean "at least one...."

[0067] As used in the specification and claims, the terms "and / or" and "and / or" are to be understood to mean "either or both" of the associated elements, i.e., both when the elements are present together or when only one of the elements is present. Unless otherwise indicated, other elements may optionally be present in addition to each element specifically identified with "and / or" or "and / or," whether or not they are associated with that element.

[0068] All references, patents, patent applications and publications cited or referred to in this application are hereby incorporated by reference in their entirety.

Claims

1. A through-air device for drying or bonding a paper web, a tissue paper web, or a nonwoven fabric web, comprising: a web transport structure configured to move; a first component including at least one sealing element adjacent to the web transport structure, the at least one sealing element configured to reduce intrusion of outside air into the through-air apparatus; at least one flow passage configured to direct air to the at least one sealing element to reduce intrusion of outside air into the through-air device; Equipped with The at least one flow passage is located within the web transport structure and is configured to direct air outwardly from the web transport structure.

2. 10. The apparatus of claim 1, wherein the first component is configured to be a fixed component, and the web transport structure is movable relative to the fixed first component.

3. 10. The apparatus of claim 1, wherein the web transport structure is a through-air roll configured for rotational movement about a first axis; the at least one flow passage configured to direct air radially outward from the through air roll.

4. The apparatus of claim 3 , wherein the first component and the at least one sealing element are located within the through-air roll.

5. 2. The apparatus of claim 1, wherein the first component includes one or more exhaust ducts, the at least one sealing element includes at least one exhaust duct sealing element, and the at least one flow path is configured to direct air to the at least one exhaust duct sealing element to reduce intrusion of outside air into the through-air apparatus.

6. 4. The apparatus of claim 3, wherein the through-air device has an active zone and an inactive zone, the first component includes an internal baffle and an inactive zone blocking plate disposed in the inactive zone of the through-air device, the at least one sealing element includes at least one blocking plate sealing element, and the at least one flow path is configured to direct air to the at least one blocking plate sealing element to reduce intrusion of outside air from the inactive zone into the through-air device.

7. The apparatus of claim 6 further comprising: a second component including at least one sealing element adjacent to the through-air roll, the at least one sealing element of the second component configured to reduce intrusion of outside air into the through-air apparatus; at least one flow passage configured to direct air to the at least one sealing element of the second component to reduce intrusion of outside air into the through-air device; Equipped with The apparatus, wherein the second component includes one or more exhaust ducts, the at least one sealing element of the second component includes at least one exhaust duct sealing element, and the at least one flow path is configured to direct air to the at least one exhaust duct sealing element to reduce intrusion of outside air into the through-air apparatus.

8. 10. The apparatus of claim 1, wherein the at least one flow path is configured to recirculate system air from another portion of the through-air apparatus to the at least one sealing element.

9. 2. The apparatus of claim 1, wherein the at least one flow path is configured to flow heated air from at least one of a Yankee hot air system exhaust flow, a vacuum pump exhaust flow, a turbine exhaust flow, and any other heated air flow to the at least one sealing element.

10. 4. The apparatus of claim 3, wherein the through-air device has an active zone and an inactive zone, the first component includes a plenum configured to cover the active zone or the inactive zone of the through-air device, and the at least one flow path is configured to direct air through the plenum to the at least one sealing element to reduce intrusion of outside air into the through-air device.

11. 2. The apparatus of claim 1, wherein the first component includes at least one of a perforated plate, a nozzle, a passage, and a slot that distributes air to the at least one sealing element.

12. 2. The apparatus of claim 1, wherein airflow through the flow passage is controlled by adjusting a fan speed, adjusting a damper position, adjusting a variable flow restriction in the flow passage or the sealing element itself, or other means to evenly distribute the air through the at least one sealing element.

13. 4. The apparatus of claim 3, wherein at least a portion of the flow path extends within the through-air roll along the first axis.

14. The apparatus of claim 1 , further comprising a fan configured to pump air through the at least one sealing element.

15. 10. The apparatus of claim 1, wherein the web transport structure is a flat bed belt configured for translational movement along a horizontal or inclined surface.

16. 1. A method of operating a through-air device for drying or bonding a papermaking web, tissue web, or nonwoven web, comprising: placing the web on a portion of a web transport structure; moving the web transport structure such that the web moves with the web transport structure; directing process air through the web transport structure, the process air flowing into a through-air device exhaust duct; providing a first component comprising at least one sealing element adjacent to the web transport structure, the at least one sealing element of the first component configured to reduce intrusion of outside air into the through-air apparatus; directing heated air to the at least one sealing element to reduce intrusion of outside air into the through-air device, wherein a source of the heated air directed to the at least one sealing element is a location other than the through-air device exhaust duct; A method comprising:

17. 17. The method of claim 16, wherein the source of heated air is at least one of preheated outside air, turbine exhaust, Yankee hot air system exhaust, vacuum pump exhaust, other heated air stream in a paper machine or paper mill environment, or any other source of heated air; A method, wherein the source of the heated air is not solely the through-air system exhaust duct.

18. A through-air device for drying or bonding a paper web, a tissue paper web, or a nonwoven fabric web, comprising: a) a rotating web transport structure having a transport surface with a plurality of openings to allow air to pass therethrough and a web wrap angle defining angular active and inactive zones of the web transport structure to form active and inactive airflow zones of the through-air device; b) a stationary structure against which the rotary web transport structure rotates relative to said stationary structure, said stationary structure being arranged to cover said inactive zone of said through-air device and comprising at least one sealing element configured to reduce in-leakage of outside air into said active zone of said through-air device compared to a comparable structure not comprising said at least one sealing element; c) at least one flow path within the stationary structure for delivering recirculated air or other heated air flow through the stationary structure to one or more of the sealing elements to further reduce in-leakage of outside air into the active zone of the through-air device; Equipped with The at least one flow passage in the stationary structure overlies the inactive zone to direct air past a non-web containing portion of the rotating web transport structure.

19. The apparatus of claim 18, wherein the source of the heated air stream is at least one of preheated outside air, a turbine exhaust, a Yankee hot air system exhaust, a vacuum pump exhaust, other heated air streams in a paper machine or paper mill environment, or any other source of heated air; An apparatus wherein the source of said heated air flow is not solely a through-air apparatus exhaust duct.

20. The method of claim 16, wherein the amount of heated air flowing to the at least one sealing element is controlled by adjusting the speed of a fan, adjusting the position of a damper, and / or adjusting a variable flow restriction portion.

Images