Foam-based manufacturing system and method

Abstract

A system comprising a pulper configured to (i) receive a surfactant, a liquid, and a fibrous stock and (ii) produce a foam suspending the fibrous stock, wherein the foam has a half-life; a headbox configured to contain the foam-suspended fibrous stock from the pulper and displace the foam-suspended fibrous stock onto a forming wire, wherein the time required for the foam-suspended fibrous stock to move from the pulper to the headbox is less than the half-life; and a foam return device that removes at least some of the foam from the forming wire and returns the at least some of the foam to the pulper.

Description

[0001] This application claims priority to and the benefit of U.S. Patent Application Serial No. 62 / 955,481, filed December 31, 2019, entitled Foam-Based Manufacturing System and Process, the entire contents of which are incorporated herein by reference. BACKGROUND

[0002] In the nonwovens field, the use of surfactants to create a foam for suspending and dispersing fiber stock is known. However, foam is difficult to manage and handle throughout the papermaking system and process because, for example, foam can migrate to undesired or unneeded system areas and cause process degradation and downtime (e.g., to remove foam from these areas). SUMMARY

[0003] Generally described, the present disclosure relates to methods and systems for managing the use of foam in manufacturing nonwoven materials. Generally described, one aspect of the subject matter described in this specification can be implemented in a system that includes a pulper configured to (i) receive a surfactant, a liquid, and a fiber stock and (ii) create a foam that suspends the fiber stock, where the foam has a half-life; a headbox configured to contain the foam-suspended fiber stock from the pulper and displace the foam-suspended fiber stock onto a forming wire, where the time required for the foam-suspended fiber stock to move from the pulper to the headbox is less than the half-life; and a foam return device that removes at least some of the foam from the forming wire and returns the at least some of the foam to the pulper. Other embodiments of this aspect include corresponding methods.

[0004] Yet another aspect of the subject matter described in this specification can be implemented in a method that includes creating a foam in a pulper; adding a fiber stock to the pulper; transporting the foam and the fiber stock to a headbox in less than or equal to a half-life of the foam; displacing the foam and the fiber stock on a forming wire; and returning at least a portion of the foam from the forming wire to the pulper. Other embodiments of this aspect include corresponding systems.

[0005] Another aspect of the subject matter described in this specification can be implemented in a system that includes a pulper configured to (i) receive a surfactant, a liquid, and a fibrous stock and (ii) produce a foam that suspends the fibrous stock, where the foam-suspended fibrous stock in the pulper has a first volume; a headbox configured to contain the foam-suspended fibrous stock from the pulper and displace the foam-suspended fibrous stock onto a forming wire, the foam-suspended fibrous stock in the headbox has a second volume, and where the second volume is equal to or greater than half of the first volume; and a foam return device that removes at least some of the foam from the forming wire and returns the at least some of the foam to the pulper. Other embodiments of this aspect include corresponding methods.

[0006] Another aspect of the subject matter described in this specification can be implemented in a system that includes a pulper configured to mix a foam and a fibrous stock; and a headbox configured to (i) contain the mixed foam and fibrous stock from the pulper without (a) adding additional surfactant between the pulper and the headbox or (b) at the headbox, and (ii) displace the mixed foam and fibrous stock onto a forming wire. Other embodiments of this aspect include corresponding methods.

[0007] Particular embodiments of the subject matter described in this specification can be implemented so as to realize one or more of the following advantages. For example, the systems described herein are provided to control the spread of foam to undesirable portions of the systems and methods, thereby avoiding the time-consuming and expensive clean-up of foam from those undesirable portions. In addition, the systems reduce (and in some cases eliminate) the need to separate and recover surfactant from liquid streams downstream of the headbox. Moreover, the systems reduce or minimize the need to add additional surfactant or foam, as the systems move the foam containing fibrous stock from the pulper to the headbox without the need to add more foam along that path. Furthermore, the systems reduce the amount of foam (and / or surfactant) that needs to be added to the pulper, as the systems recover foam from the headbox and forming wire and return the foam to the pulper by creating a closed-loop type system for managing the foam from the pulper to the headbox and then back to the pulper.

[0008] The details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims. BRIEF DESCRIPTION OF DRAWINGS

[0009] FIG. 1A is a block diagram of an example nonwoven system for producing a foam formed product.

[0010] FIG. 1B is a second block diagram of an example nonwoven system for producing a foam formed product.

[0011] FIG. 2 is a flowchart of an example method of using foam in a nonwoven system.

[0012] Repetition of reference numerals in the present description and drawings is intended to represent the same or similar features or elements. DETAILED DESCRIPTION

[0013] The present disclosure generally relates to the use of foam in a manufacturing process to produce a nonwoven material. For example, a system for such a manufacturing process includes a pulper that receives fibers, a liquid (e.g., water), and a surfactant. The pulper mixes (e.g., agitates) the surfactant and liquid together to produce a foam. The pulper also mixes the foam with the fibers to produce a foam suspension of fibers, where the foam holds and separates the fibers to facilitate uniform or near-uniform distribution of the fibers within the foam (e.g., as an artifact of the mixing process in the pulper). The uniform distribution of fibers facilitates desired nonwoven material characteristics, including, for example, strength and visual appearance of mass.

[0014] The foam suspension of fibers is then delivered to a headbox that lays the fibers on a forming wire to form a matrix of fibers. Given that the foam loses its volume over time (e.g., deflates as the bubbles that form the foam collapse), the distribution of fibers in the foam tends to become less uniform or non-uniform as the fibers clump together without the bubbles separating them.

[0015] Accordingly, to reduce the likelihood of the fiber suspension, e.g., losing its uniformity, the system delivers the fiber suspension from the pulper to the headbox (and optionally back) in less than the half-life of the foam, which causes at least half of the foam and corresponding bubble content that was produced at the pulper to enter the headbox. With at least half of the initial amount of foam, the fiber suspension is likely to maintain good fiber uniformity / distribution.

[0016] Further, the system can also recover at least some of the foam deposited on the wire and return the recovered foam directly to the pulper (e.g., within the half-life of the foam). For example, the system collects the foam deposited on the wire and transports the foam to the pulper without any intermediate equipment designed to collapse the foam or separate the foam into its constituent parts and / or return the foam (e.g., any mass of foam) or its constituent parts directly to the headbox. The system and method will be discussed below with reference to FIG. 1A and 1B are discussed in more detail.

[0017] FIG. 1A is a block diagram of an example nonwoven system 100 that produces a foam formed product, FIG. 1B is a second block diagram of an example nonwoven system 100 that produces a foam formed product.

[0018] A foam formed product is a product formed from a suspension that includes a mixture of solids, liquids, and dispersed air bubbles. The solids in the suspension of the foam formed product can include solid particles, such as natural and / or man-made fibers. Other solids that can be added in the suspension include superabsorbent materials, such as activated carbon, microencapsulated active ingredients, calcium carbonate, titanium dioxide. The liquids in the suspension of the foam formed product can include water, for example. In some embodiments, a surfactant can be used in the suspension, for example. The suspension of the foam formed product can include air as the gaseous component forming the dispersed air bubbles, for example. In some embodiments, the air content within the suspension can be in the range of about 20% to about 95% or about 30% to about 80%. In some embodiments, the air bubbles can include alternative or additional gases.

[0019] In some embodiments, a foam is first formed by mixing a liquid (e.g., water) with a foaming agent, for example. The foaming agent can include or be a surfactant, for example. The surfactant included in the suspension of the foam formed product can be selected from anionic, cationic, nonionic, zwitterionic, and amphoteric surfactants, for example.

[0020] Example amphoteric surfactants include, but are not limited to, coco-betaine, cocoamidopropyl betaine, and octyl / decyl amidopropyl betaine, cocoamidopropyl hydroxysultaine, cocoamidopropyl and lauramine oxide, example anionic surfactants include sodium lauryl sulfate, potassium laureth phosphate, sodium isethionate, example cationic cetrimonium chloride, and example nonionic surfactants include laureth ether 23, laureth ether 30, PEG-7 glyceryl cocoate, caprylyl / octyl glucoside, lauryl glucoside, decyl glucoside, and coco-glucoside.

[0021] In some embodiments, the surfactant is typically present in an amount greater than about 0.2 wt.%, 0.5 wt.% or 1 wt.%, for example, in an amount greater than about 5 wt.%, for example, in an amount greater than about 10 wt.%, for example, in an amount greater than about 15 wt.% in combination with the liquid. The one or more surfactants are typically present in an amount less than about 50 wt.%, for example, in an amount less than about 40 wt.%, for example, in an amount less than about 30 wt.%, for example, in an amount less than about 20 wt.%.

[0022] Referring to FIG. 1A The pulper 102 receives the surfactant 104, the liquid (e.g., water) 106, and the fibrous stock 108 and produces a froth of the suspended fibrous stock 108 in the pulper 102. In some embodiments, the pulper 102 includes one or more mixing blades that mix or blend the surfactant 104 and the liquid 106 to form a froth and (subsequently or concurrently) mix or blend the fibrous stock 108 with the froth to form a froth-suspended fibrous stock 110, which is a blend or mixture of the fibrous stock 108 in the froth produced by the liquid 106 and the surfactant 104. More generally, a froth generally refers to a porous matrix that is an aggregation of hollow cells or bubbles that can be interconnected to form channels or capillaries. For example, due to the mixing process of the pulper 102, individual fibers of the fibrous stock 108 are distributed (e.g., uniformly) throughout the froth in these channels or capillaries.

[0023] The fibers in the fibrous stock 108 can include various natural or synthetic cellulosic fibers, including but not limited to non-wood fibers such as cotton, abaca, kenaf, Indian grass, flax, thatch, straw, jute, bagasse, milkweed floss fiber, and pineapple leaf fiber; and wood or pulp fibers such as those obtained from deciduous and coniferous trees, including softwood fibers such as northern and southern softwood kraft fibers; hardwood fibers such as eucalyptus, maple, birch, and aspen. The pulp fibers can be prepared in high-yield or low-yield form and can be pulped by any known method, including kraft, sulfite, high-yield pulping methods, and other known pulping methods. Fibers prepared by organic solvent pulping methods can also be used.

[0024] The foam density of the foam can vary depending on the particular application and various factors including the fiber stock 108 used. In some embodiments, for example, the foam density of the foam can be greater than about 100 g / L, such as greater than about 250 g / L, such as greater than about 300 g / L. The foam density is typically less than about 800 g / L, such as less than about 500 g / L, such as less than about 400 g / L, such as less than about 350 g / L. In some embodiments, for example, a lower density foam having a foam density typically less than about 350 g / L, such as less than about 340 g / L, such as less than about 330 g / L is used. The air content of the foam will typically be greater than about 20%, such as greater than about 50%, such as greater than about 60%. The air content is typically less than about 95% by volume, such as less than about 70% by volume, such as less than about 65% by volume.

[0025] In some embodiments, a portion of the fibers in the fiber stock 108, such as greater than ten percent and up to one hundred percent, can be synthetic fibers, such as rayon, polyolefin fibers, polyester fibers, bicomponent sheath-core fibers, multicomponent binder fibers, and the like. An exemplary polyethylene fiber is Minifiber® available from Minifibers, Inc. (Jackson City, Tenn.). Any known bleaching method can be used. Synthetic cellulosic fiber types include all varieties of rayon and other fibers derived from viscose or chemically modified cellulose. Chemically treated natural cellulosic fibers such as mercerized pulp; chemically stiffened, debonded or crosslinked fibers; or sulfonated fibers can be used. In order to achieve good mechanical properties when using papermaking fibers, it can be desirable for the fibers to be relatively undamaged and mostly unrefined or only lightly refined. While recycled fibers can be used, virgin fibers are often useful because of their mechanical properties and lack of contaminants. Mercerized fibers, regenerated cellulose fibers, cellulose produced by microorganisms, rayon, and other cellulosic materials or cellulose derivatives can be used. Suitable papermaking fibers can also include recycled fibers, virgin fibers, or mixtures thereof.

[0026] Other papermaking fibers that can be used in the fiber stock 108 include secondary or recycled fibers as well as high yield fibers. High yield pulp fibers are those papermaking fibers manufactured by pulping processes that provide a yield of about 65% or more, more specifically about 75% or more, still more specifically about 75% to about 95%. Yield is the amount of resulting processed fiber expressed as a percentage of the original wood mass. Such pulping processes include bleached chemi-thermo mechanical pulp (BCTMP), chemi-thermo mechanical pulp (CTMP), pressure / pressure thermo mechanical pulp (PTMP), thermo mechanical pulp (TMP), thermo mechanical chemical pulp (TMCP), high yield sulfite pulp, and high yield kraft pulp, all of which result in fibers having a high level of lignin. High yield fibers are well known for their stiffness relative to typical chemically pulped fibers, both in the dry and wet states.

[0027] The foam-suspended fiber stock 110 is delivered from the pulper 102 to the headbox 112 by a conduit 118, such as a plastic composite or metal pipe or tube. In some embodiments, there can be equipment or other processing aids between the pulper 102 and the headbox 112, while in other embodiments, such additional equipment, including equipment to dilute the foam-suspended fiber stock, is not present. The headbox 112 then displaces the foam-suspended fiber stock 110 onto the forming wire 114, as referenced in FIG. 1B More detail is described.

[0028] The system 100 moves the foam-suspended fiber stock 110 from the pulper 102 to the headbox 112 in less time than the half-life of the foam, once the foam-suspended fiber stock 110 is sufficiently mixed, such as determined by a predetermined schedule. The half-life of a foam is the time required for half the mass (or volume) of the liquid 106 and surfactant 104 (or other specified constituent components) that formed the foam to defoam after the foam is formed. For example, if one hundred grams of the liquid 106 and surfactant 104 are combined to form a foam, then the half-life of the foam is the time required for fifty grams of the foam to defoam into a liquid form, once the foam is formed.

[0029] As described above, the foam maintains the fiber stock 108 evenly (or quasi-evenly) distributed, such that a majority (or more than 60, 70, 80, 90, or 95%) of the fibers are separated and not clumped or tangled together. However, once the foam defoams to less than half of its original mass or liquid volume (e.g., compared to the case where the foam is fully or substantially foamed in the pulper 102, such as at least ninety percent foamed), there is not enough foam (e.g., gas bubble content) to maintain the desired evenness of fiber distribution.

[0030] In some embodiments, the pulper 102 produces the foamed fiber stock 110 having a first volume, and the system 100 delivers the foamed fiber stock 110 to the headbox 112 such that the foamed fiber stock 110 has a second volume in the headbox 112 that is equal to or greater than half of the first volume. This volume comparison helps ensure that enough foam remains at the headbox 112 to provide the desired fiber distribution uniformity. In some embodiments, the first and second volumes are measured in terms of the entire foamed fiber stock 110 (i.e., the foam and fiber stock 108), while in other embodiments, the first and second volumes are measured in terms of the foam alone.

[0031] Accordingly, the system 100 can be designed, for example, with a conduit 118 to ensure that the travel time of the foamed fiber stock 110 between the pulper 102 and the headbox 112 is less than the half-life of the foam to ensure that the foamed fiber stock 110 travels through the conduit 118 (and / or other system 100 components) between the pulper 102 and the headbox 112 fast enough such that, given the length of the conduit 118, the foamed fiber stock 110 reaches the headbox 112 in less time than the half-life of the foam, or some combination thereof. In some embodiments, the conduit 118 connects the pulper directly to the headbox, where directly means that there are no intermediate devices or equipment between the pulper 102 and the headbox 112 that are used to adjust the consistency of the fiber by more than, for example, 25%, 50%, 100%, or 250%.

[0032] The half-life of various foams was measured according to the following test method.

[0033] 1. Pour 100 mL of the surfactant 104 and liquid 106 solution into a Hamilton Beach B70 blender, model 58161, A4461CE series.

[0034] 2. Blend the solution at high speed for 10 seconds while opening the top flap of the blender to let air in to create a foam.

[0035] 3. Immediately pour the foam into a 250 mL graduated cylinder and start a stopwatch.

[0036] 4. Record the time it takes for the liquid line at the bottom of the graduated cylinder to reach 50 mL, thereby recording the time it takes for the foam to collapse to half-life.

[0037] Exemplary cationic and nonionic surfactant-based foams were tested according to this method, as shown in Table 1 below:

[0038]

[0039] Table 1

[0040] More generally, the half-life of some bubbles can range from about thirty seconds to five minutes.

[0041] Given that system 100 is designed to ensure that the foam-suspended fiber feedstock 110 reaches the headbox 112 within the half-life of the foam to promote good fiber distribution uniformity, in some embodiments, it is not necessary to add additional surfactant 104 (or foam) between the pulper 102 and the headbox 112. Not requiring additional surfactant means that no amount of surfactant 104 is added. The amount of surfactant 104 is at most 10 percent of the initial amount of surfactant added for foam formation, or preferably at most 5 percent, more preferably at most 2 percent, and most preferably no additional surfactant is added.

[0042] Similarly, in some embodiments, it is not necessary to add additional liquid 106 between the pulper 102 and the headbox 112. "Not requiring additional liquid 106" means that no amount of liquid 106 is added. The amount of liquid 106 is at most 10 percent of the initial amount of liquid 106 added for foam formation, or preferably at most 5 percent, more preferably at most 2 percent, and most preferably no additional liquid 106 is added.

[0043] As described above, the foam-suspended fiber material 110 is fed from the pulper 102 into the headbox 112. In some embodiments, the headbox 112 is a single-chamber headbox (meaning it is designed to lay one layer of fiber at a time), and in other embodiments, it may be a multi-layer headbox 112 (meaning it is designed to lay more than one layer of fiber). FIG. 1B The headbox 112 shown is, for example, a three-chamber headbox 112.

[0044] for FIG. 1B The headbox allows the fiber material 110 for the first layer of foam suspension to be fed into the first chamber 112a, the fiber material 110 for the second layer of foam suspension to be fed into the second chamber 112b, and the fiber material 110 for the third layer of foam suspension to be fed into the third chamber 112c, thereby allowing the manufacture of a three-layer foam molded product (although the concept can also be extended to other multi-layer foam molded products). The fiber composition or blend of the fiber material 110 for each layer of foam suspension can be the same or different from each other. In some embodiments, starting from the headbox 112, layers of foam suspension fiber material 110 are fed onto a continuously moving forming wire 114 supported and driven by rollers 128 to form (e.g., a single sheet) a three-layer foam molded product.

[0045] In some embodiments, the consistency of the foam to the fibrous stock (e.g., the weight ratio of the fibrous stock 108 to the foam) in the pulper 102 and the headbox 112 is about 0.5% to 3%, 0.8 to 3%, or about 0.75% to 3%, or about 1% to 3%, or about 1% to 2%. In some embodiments, the consistency of the foam to the fibrous stock varies by no more than 10%, 25%, 50%, or 100% between the pulper 102 and the headbox 112.

[0046] Once (or as) the foam-suspended fibrous stock 110 is displaced on the forming wire 114, the foam return device 116 can remove the foam (and / or the surfactant 104 and the liquid 106) from the foam-suspended fibrous stock 110. In some embodiments, the foam return device 116 is a device that includes one or more vacuum boxes that apply suction or a vacuum to the underside of the forming wire 114 to pull the foam and / or components thereof out of the displaced foam-suspended fibrous stock 110.

[0047] In some embodiments, an excess liquid removal device 117 (e.g., a vacuum box) can be used as the displaced foam-suspended fibrous stock 110 is conveyed downstream. From the forming wire 114, the displaced foam-suspended fibrous stock 110 can be conveyed, for example, downstream and dried on an air dryer.

[0048] As described above, the foam return device 116 can facilitate returning the foam to the pulper 102. More specifically, in some embodiments, the foam return device 116 removes at least some of the foam from the forming wire 114 (and / or as the foam-suspended fibrous stock 110 is laid on the wire 114) and returns the foam to the pulper 102 for further use. In some embodiments, returning at least some of the foam to the pulper 104 includes returning at least some of the surfactant 104 (e.g., when some of the foam has defoamed into the surfactant 104 and the liquid 106), some of the surfactant 104 and the liquid 106 (e.g., as some of the foam has defoamed into the surfactant 104 and the liquid 106), some of the foam (e.g., that has not yet defoamed), or some combination thereof. For example, once some (or all) of the surfactant 104 or foam has been removed from the displaced foam-suspended fibrous stock 110, a conduit 120 (part of the foam return device 116) can return at least some of the surfactant 104 and the liquid 106 or the foam to the pulper 102.

[0049] In some embodiments, returning at least some of the foam (or surfactant 104 and / or liquid 106 (if some defoaming has occurred)) from the forming wire 114 back to the pulper 102 means returning at least 70%, or 80%, or 90% of the foam mass or liquid volume (e.g., in the headbox) back to the pulper 102, and optionally returning the foam (or surfactant 104 and / or liquid 106 (if some defoaming has occurred)) back to the pulper 102 within the half-life of the foam. The liquid volume or mass of foam is the target liquid volume or mass of foam in the headbox during normal (steady state) operation of the system 100, respectively. Thus, the goal is to return as much foam back to the pulper 102 as possible to reduce the need to add more foam (or surfactant 104 or liquid 106) to the pulper 102. This creates a closed loop for the foam to travel back and forth between the pulper 102 and the headbox 112 / forming wire 114.

[0050] In some embodiments, the conduit 120 connects the foam return device 116 and the pulper 102 directly. Directly connected here means that there are no intermediate devices or equipment between the foam return device 116 and the pulper 102 that are designed to defoam the foam or store the foam, surfactant, and / or liquid to separate the surfactant 104 and the liquid 106.

[0051] In some conventional systems, there is a return line from the vacuum box (e.g., a 116-type device) under the wire (e.g., 114) back to the headbox to transfer the liquid (e.g., 106) collected from the forming wire to the headbox (e.g., 112) to manage the fiber consistency of the headbox. In some embodiments, the system 100 does not have such a return line (e.g., 126) or returns no more than 10%, 20%, 30%, 40%, or 50% of the foam, surfactant 104, and / or liquid 106 (e.g., without passing through the pulper 102) back to the headbox 112.

[0052] Thus, the structure and configuration of the system 100 is designed to prevent the foam (including the surfactant 104) from spreading to other parts of the system 100, for example, by reducing the amount of surfactant needed in the system, for example, by ensuring that the foam-suspended fiber stock 110 reaches the headbox 112 within the half-life of the foam, thus not requiring additional surfactant / foam to be added to maintain a good foam volume / content and thus a good uniform fiber distribution to help achieve the process benefits described above.

[0053] The basis weight of the absorbent article 100 produced according to the present disclosure can vary depending on the end product. For example, the process can be used to produce paper towels, tissue products, industrial wipers, and the like.

[0054] FIG. 2is a flowchart of an exemplary process 200 of using a foam in a nonwoven system 100.

[0055] The foam is generated in a pulper (202). For example, the pulper 102 generates the foam from the surfactant 104 and the liquid 106.

[0056] The fibrous stock is added to the pulper (204). For example, the fibrous stock 108 is added to the pulper 102 and mixed with the foam simultaneously with or after the surfactant 104 and the liquid 106.

[0057] The foam and the fibrous stock are transported to a headbox in less than or equal to a half-life of the foam (206). For example, the foam and the fibrous stock 108 are transported to the headbox 112 in less than or equal to the half-life of the foam.

[0058] The foam and the fibrous stock are displaced on a forming wire (208). For example, the headbox 112 displaces the foam and the fibrous stock 108 (e.g., the foam-suspended fibrous stock 110) on the forming wire 114.

[0059] At least a portion of the foam is returned from the forming wire to the pulper (210). For example, the foam return device 116 (and the conduit 120) returns a portion of the foam (or the surfactant 104) to the pulper 102, e.g., within the half-life of the foam.

[0060] Embodiments

[0061] Embodiment 1. A system comprising a pulper configured to (i) receive a surfactant, a liquid, and a fibrous stock and (ii) generate a foam that suspends the fibrous stock, wherein the foam has a half-life; a headbox configured to receive the foam-suspended fibrous stock from the pulper and displace the foam-suspended fibrous stock onto a forming wire, wherein the foam-suspended fibrous stock moves from the pulper to the headbox in less than the half-life; and a foam return device that removes at least some of the foam from the forming wire and returns the at least some of the foam to the pulper, wherein the at least some of the foam moves from the foam return device to the pulper in less than the half-life.

[0062] Embodiment 2. The system of Embodiment 1, wherein the at least some of the foam that is returned to the pulper remains in a foamed state from the forming wire to the pulper.

[0063] Embodiment 3. The system of any of the preceding embodiments, wherein the surfactant is one of cocoglycoside and cetrimonium chloride.

[0064] Embodiment 4. The system of any of the preceding embodiments, wherein the half-life is thirty seconds to five minutes.

[0065] Embodiment 5. The system of any of the preceding embodiments, comprising an excess liquid removal device.

[0066] Embodiment 6. The system of any of the preceding embodiments, wherein the foam- suspended fiber stock in the headbox has a consistency of about 0.5% to 3%.

[0067] Embodiment 7. The system of any of the preceding embodiments 1-5, wherein the foam- suspended fiber stock in the headbox has a consistency of about 0.75% to 3%.

[0068] Embodiment 8. The system of any of the preceding embodiments 1-5, wherein the foam- suspended fiber stock in the headbox has a consistency of about 1% to 3%.

[0069] Embodiment 9. The system of any of the preceding embodiments, comprising a conduit directly connecting the pulper to the headbox.

[0070] Embodiment 10. The system of any of the preceding embodiments, wherein the foam return device is directly connected to the pulper.

[0071] Embodiment 11. The system of embodiment 10, wherein the foam return device comprises a conduit.

[0072] Embodiment 12. A method comprising generating a foam in a pulper; adding a fiber stock to the pulper; transporting the foam and the fiber stock to a headbox in a time less than or equal to a half-life of the foam; displacing the foam and the fiber stock on a forming wire; and returning at least a portion of the foam from the forming wire to the pulper.

[0073] Embodiment 13. The method of embodiment 12, wherein the generating and the adding are performed simultaneously.

[0074] Embodiment 14. The method of embodiments 12 or 13, wherein transporting the foam and the fiber stock to a headbox in a time less than or equal to a half-life of the foam comprises transporting the foam and the fiber stock to a headbox in a time less than or equal to a half-life of the foam without adding water during the transporting.

[0075] Embodiment 15. The method of any of embodiments 12-14, wherein the foam and the fibrous stock in the headbox have a fiber consistency of about 0.5% to 3%.

[0076] Embodiment 16. The method of any of embodiments 12-14, wherein the foam and the fibrous stock in the headbox have a fiber consistency of about 0.75% to 3%.

[0077] Embodiment 17. The method of any of embodiments 12-14, wherein the foam and the fibrous stock in the headbox have a fiber consistency of about 1% to 3%.

[0078] Embodiment 18. A system comprising a pulper configured to mix a foam and a fibrous stock; and a headbox configured to (i) receive the mixed foam and fibrous stock from the pulper without (a) adding additional surfactant between the pulper and the headbox or (b) at the headbox, and (ii) displace the mixed foam and fibrous stock onto a forming wire.

[0079] Embodiment 19. The system of embodiment 18, comprising a foam return device that removes at least some of the foam from the forming wire and returns the at least some of the foam to the pulper.

[0080] Embodiment 20. A system comprising a pulper configured to (i) receive a surfactant, a liquid, and a fibrous stock and (ii) produce a foam suspending the fibrous stock, wherein the foam-suspended fibrous stock in the pulper has a first volume; a headbox configured to receive the foam-suspended fibrous stock from the pulper and displace the foam-suspended fibrous stock onto a forming wire, the foam-suspended fibrous stock in the headbox having a second volume, and wherein the second volume is equal to or greater than half of the first volume; and a foam return device that removes at least some of the foam from the forming wire and returns the at least some of the foam to the pulper.

[0081] Embodiment 21. The system of embodiment 20, wherein the at least some of the foam returned to the pulper remains in a foamed state from the forming wire to the pulper.

[0082] Embodiment 22. The system of embodiment 20 or 21, wherein the surfactant is one of cocoglucoside and cetrimonium chloride.

[0083] While the specification contains many specifics, these should not be construed as limiting the scope of any invention or patentable subject matter an claimed. Rather, these specifics are provided to describe a particular implementation of a particular invention. Some features could be readily combined with other features to produce a new and / or alternative invention. Repetition of disclosure of these features does not exclude these identical features from being used in combination with each other and the disclosure is deemed to contain whatever comprises a combination of these elements.

[0084] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring such order nor that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing can be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations.

[0085] This written description does not limit the invention to the precise terms set forth. Accordingly, while the specification has been described above in terms of exemplary embodiments, it is to be understood that person of ordinary skill in the art can make modifications, alterations, and variations to the described examples without the departing from the scope of the application.

Claims

1. A system comprising: a pulper configured to (i) receive a surfactant, a liquid, and a fibrous stock, (ii) create a foam suspending the fibrous stock, and (iii) mix the surfactant, the liquid, and the fibrous stock; and wherein the foam has a half-life; a headbox configured to hold the foam-suspended fibrous stock from the pulper and displace the foam-suspended fibrous stock onto a forming wire; a conduit directly connecting the pulper to the headbox such that no intermediate equipment is needed to adjust consistency of the fibrous stock between the pulper and the headbox, and wherein the conduit is configured to move the foam-suspended fibrous stock from the pulper to the headbox in less than the half-life; and a foam return device that removes at least some of the foam from the forming wire and returns the at least some of the foam to the pulper, wherein the at least some of the foam from the foam return device to the pulper takes less than the half-life, wherein the foam return device is directly connected to the pulper.

2. The system of claim 1, wherein the at least some of the foam returned to the pulper remains in a foamed state from the forming wire to the pulper.

3. The system of claim 1, wherein the surfactant is one of cocoglucoside and cetrimonium chloride.

4. The system of claim 1, wherein the half-life is thirty seconds to five minutes.

5. The system of claim 1, comprising an excess liquid removal device.

6. The system of claim 1, wherein the foam-suspended fibrous stock in the headbox has a consistency of 0.5% to 3%.

7. The system of claim 6, wherein the foam-suspended fibrous stock in the headbox has a consistency of 0.75% to 3%.

8. The system of claim 6, wherein the foam-suspended fibrous stock in the headbox has a consistency of 1% to 3%.

9. The system of claim 1, wherein the foam return device comprises a conduit.

10. A method comprising: creating a foam in a pulper; adding a fibrous stock to the pulper; mixing the foam and the fibrous stock in the pulper; transporting the foam and the fibrous stock to a headbox in less than or equal to a half-life of the foam by a conduit directly connecting the pulper to the headbox such that no intermediate equipment is needed to adjust consistency of the fibrous stock between the pulper and the headbox; displacing the foam and the fibrous stock on a forming wire; and returning at least a portion of the foam from the forming wire to the pulper in less than or equal to the half-life of the foam.

11. The method of claim 10, wherein the creating and the adding are simultaneous.

12. The method of claim 10, wherein the delivering the foam and the fiber stock to a headbox in a time less than or equal to a half-life of the foam includes delivering the foam and the fiber stock to a headbox in a time less than or equal to a half-life of the foam without adding water during the delivering.

13. The method of claim 10, wherein the foam and the fiber stock in the headbox have a fiber consistency of 0.5% to 3%.

14. The method of claim 10, wherein the foam and the fiber stock in the headbox have a fiber consistency of 0.75% to 3%.

15. The method of claim 10, wherein the foam and the fiber stock in the headbox have a fiber consistency of 1% to 3%.

16. A system comprising: a pulper configured to mix a foam and a fiber stock; a headbox; a conduit directly connecting the pulper to the headbox such that no intermediate equipment is needed to adjust a consistency of the fiber stock between the pulper and the headbox, and wherein the conduit is configured to move the mixed foam and fiber stock from the pulper to the headbox in a time less than a half-life of the foam; and wherein the headbox is configured to (i) contain the mixed foam and fiber stock from the pulper without adding additional surfactant (a) between the pulper and the headbox or (b) at the headbox, and (ii) displace the mixed foam and fiber stock onto a forming wire; the system includes a foam return device that removes at least some of the foam from the forming wire and returns the at least some of the foam to the pulper, wherein the foam return device is directly connected to the pulper.

17. A system comprising: a pulper configured to (i) receive a surfactant, a liquid, and a fiber stock, (ii) produce a foam suspending the fiber stock, and (iii) mix the surfactant, the liquid, and the fiber stock, and wherein the foam-suspended fiber stock in the pulper has a first volume; a headbox; a conduit directly connecting the pulper to the headbox such that no intermediate equipment is needed between the pulper and the headbox, wherein the headbox is configured to contain the foam-suspended fiber stock from the pulper and displace the foam-suspended fiber stock onto a forming wire, the foam-suspended fiber stock in the headbox has a second volume, and wherein the second volume is equal to or greater than half of the first volume; and a foam return device that removes at least some of the foam from the forming wire and returns the at least some of the foam to the pulper, wherein the foam return device is directly connected to the pulper.

18. The system of claim 17, wherein the at least some of the foam returned to the pulper from the forming wire remains in a foamed state from the forming wire to the pulper.

19. The system of claim 17, wherein the surfactant is one of cocoglucoside and cetrimonium chloride.

20. A system comprising: a pulper configured to (i) receive a surfactant, a liquid, and a fibrous stock, (ii) produce a foam suspending the fibrous stock, and (iii) mix the surfactant, the liquid, and the fibrous stock; a headbox; a conduit directly connecting the pulper to the headbox such that no intermediate equipment is needed between the pulper and the headbox, wherein the headbox is configured to receive the foam-suspended fibrous stock from the pulper and displace the foam-suspended fibrous stock onto a forming wire, wherein the foam present in the headbox has a liquid volume; and a foam return device that removes at least some of the foam from the forming wire and returns at least fifty percent (50%) of the liquid volume of the foam to the pulper, wherein the foam return device is directly connected to the pulper.

21. The system of claim 20, wherein the foam return device returns at least sixty percent (60%) of the liquid volume of the foam to the pulper.

22. The system of claim 21, wherein the foam return device returns at least seventy percent (70%) of the liquid volume of the foam to the pulper.

23. The system of claim 22, wherein the foam return device returns at least eighty percent (80%) of the liquid volume of the foam to the pulper.

24. The system of claim 23, wherein the foam return device returns at least ninety percent (90%) of the liquid volume of the foam to the pulper.

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